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Philips Semiconductors
Product specification
1GHz LNA and mixer
NE/SA600
AC ELECTRICAL CHARACTERISTICS1,2
SYMBOL PARAMETER TEST CONDITIONS LIMITS -3 TYP +3 UNITS
LNA (VCC = VCCMX = +5V, TA = 25C; Enable = Hi, Test Figure 1, unless otherwise stated.) S21 S21 S21/T S21/T S21/f S12 S11 S22 P-1dB IP3 Amplifier gain Amplifier gain in thru mode Gain temperature sensitivity enabled Gain temperature sensitivity in thru mode Gain frequency variation Amplifier reverse isolation Amplifier input match3 Amplifier output match Amplifier input 1dB gain compression Amp input 3rd-order intercept Amp input 3rd-order intercept (thru mode) Amplifier noise figure NF tON tOFF Amp noise figure w/shunt 15nH inductor at input Amplifier turn-on time Amplifier turn-off time 900MHz Enable = LO, 900MHz 900MHz Enable = LO, 900MHz 800MHz - 1.2GHz 900MHz 900MHz 900MHz 900MHz Test Fig. 2, 900MHz Test Fig. 2, 900MHz, Enable = LO 900MHz 900MHz Enable Lo Hi Enable Hi Lo Coupling = 100pF Coupling = 0.01F Coupling = 100pF Coupling = 0.01F 1.9 1.7 -47 -11 -16.8 -21.2 -11.6 14.9 -9.0 16 -7.5 -0.008 -0.014 -0.014 -42 -10 -15 -20 -10 +26 2.2 2.0 30 3 10 1 2.5 2.3 -37 -9 -13.2 -18.8 -8.6 17.1 -6.0 dB dB dB/C dB/C dB/MHz dB dB dB dBm dBm dBm dB dB s ms s ms
Mixer (VCC = VCCMX = +5V, TA = 25C, Enable = Hi, fLO = 1GHz @ 0dBm, fRF = 900MHz, fIF = 100MHz, Test Fig. 1, unless otherwise stated) VGC PGC S11RF NFM P-1dB IP3INT IP2INT GRFM-IF GLO-IF GLO-RFM S11LO GLO-RF Mixer voltage conversion gain Mixer power conversion gain Mixer input match Mixer SSB noise figure Mixer input 1dB gain compression Mixer input third order intercept Mixer input second order intercept Mixer RF feedthrough Mixer LO feedthrough Local oscillator to mixer input feedthrough LO input match Local oscillator to RF input feedthrough RL1 = RL2 = 1k RL1 = RL2 = 1k 900MHz Test Fig. 3, 900MHz, fIF = 80MHz 900MHz 900MHz 900MHz 900MHz, CIF = 3pF 900MHz, CIF = 3pF 900MHz 900MHz 900MHz 900MHz -24 9.5 -3.05 -23 12.2 -5.3 +5 +18 10.4 -2.6 -20 14 -4 +6 +20 -7 -10 -33 -20 -46 -39 -16 11.3 -2.15 -17 15.8 -2.7 +7 +22 dB dB dB dB dBm dBm dBm dB dB dB dB dB dB
GRFO-RFM Filter feedthrough
LNA + Mixer (VCC=VCCMX=+5V, TA=25C, Enable=Hi, fLO=1GHz @ 0dBm, fRF = 900MHz, fIF = 100MHz, Test Fig. 1, unless otherwise stated) PGC NF IP3 Overall power conversion gain Overall noise figure Overall input 3rd-order intercept 13.4 3.5 -13 dB dB dBm
NOTE: 1. All meausrements include the effects of the NE/SA600 Evaluation Board (see Figure ) unless otherwise noted. Measurement system impedance is 50. 2. Standard deviations are estimated from design simulations to represent manufacturing variations over the life of the product. 3. With a shunt 15nH inductor at the input of the LNA, the value of S11 is typically -15dB.
1993 Dec 15
49
Philips Semiconductors
Product specification
1GHz LNA and mixer
NE/SA600
TYPICAL APPLICATION
+5V
TEST FIGURE 1
+5V
1 0.1F 2 RF INPUT 900MHz 3 100pF 4 BYPASS 0.01F 6 7 100pF 5
14 13 12 RFC 10H
RL1 1k IF OUT 100MHz 1k RL2 0.1F
1 2 RF INPUT 900MHz 3 0.01F 4 BYPASS 1F 6 5
14 13
RFC 10H IF OUT 0.01F 50
IF FILTER
12
NE/SA600
11 10 9
RF IN MX IMAGE REJECTION FILTER RF OUT A
NE/SA600
RF IN MX 11 0.01F 10 9 0.01F RF OUT A 8
8 0.01F POWER-DOWN CONTROL
7
POWER-DOWN CONTROL LO INPUT 0dBm 1.0GHz
LO INPUT 0dBm 1.0GHz NOTES: RATIO OF BYPASS TO SIGNAL COUPLING CAPS FOR LNA SHOULD BE 100:1 OR GREATER. IF FILTER SHOULD BE AC COUPLED.
TEST FIGURE 2
TEST FIGURE 3
+5V
+5V
1 0.1F 2 RF INPUT 900MHz 3 100pF 4 BYPASS 0.01F 6 7 100pF 5
14 RFC 10H 13 12
RL1 1k 470nH 4.7pF RF IN MX IF OUT 50 RF INPUT 900MHz 0.1F
1 2 3 0.01F 4 BYPASS 1F 5 6
14 13 12 RFC 10H
RL1 1k 470nH IF OUT 4.7pF 50
0.01F
0.01F
NE/SA600
11 100pF 10 9
NE/SA600
11 0.01F 10 9 0.01F
RF IN MX IMAGE REJECTION FILTER RF OUT A
100pF RF OUT A 8 0.01F POWER-DOWN CONTROL LO INPUT 0dBm 1.0GHz LO INPUT 0dBm 1.0GHz 7 8
POWER-DOWN CONTROL
SR00084
Figure 3. Test Application and Test Figures 1, 2 and 3
1993 Dec 15
50
Philips Semiconductors
Product specification
1GHz LNA and mixer
NE/SA600
NOTE: All performance curves include the effects of the NE/SA600 evaluation board.
LNA S21 CHARACTERISTICS 4.5V VCC = VCCMX 5.5V, Test Figure 1, unless otherwise specified.
LNA S21 vs Frequency
40 20
LNA S21 vs Frequency
30 ENABLE=HI S21 MAGNITUDE (dB) S21 MAGNITUDE (dB) 20
15 ENABLE=HI 10
10
5
0
0
-10
ENABLE=LO -5 ENABLE=LO
-20 10 100 FREQUENCY (MHz) 1000 2000
-10 800 900 1000 1100 FREQUENCY (MHz) 1200
LNA S21 Phase vs Frequency
0 18
LNA S21 vs Frequency and VCC
-20
17.5
-40 S21 MAGNITUDE (dB) S21 PHASE (Deg)
17
-60
16.5
-80
16
-100
15.5
VCC = 4.5V VCC = 5.0V VCC = 5.5V
-120 800 900 1000 1100 FREQUENCY (MHz) 1200
15 800 900 FREQUENCY (MHz) 1000
LNA S21 vs Frequency and Temperature
20 18 -40C 16 S21 MAGNITUDE (dB) S21 MAGNITUDE (dB) 14 25C 12 10 8 6 4 2 0 800 900 1000 1100 1200 FREQUENCY (MHz) 85C
LNA Thru S21 vs Frequency and Temperature
0
-2
-4
-6 -40C -8 25C -10 85C
-12 800 900 1000 FREQUENCY (MHz) 1100 1200
SR00085
Figure 4. LNA S21 Performance Characteristics 1993 Dec 15 51
Philips Semiconductors
Product specification
1GHz LNA and mixer
NE/SA600
LNA S11/S12/S22 CHARACTERISTICS 4.5V VCC = VCCMX 5.5V, Test Figure 1, unless otherwise specified.
LNA S11 vs Frequency and Temperature
0 -2 -10 -4 S12 MAGNITUDE (dB) -6 S11 MAGNITUDE (dB) -8 -10 -12 -14 -16 -18 -20 800 900 1000 FREQUENCY (MHz) 1100 1200 -80 10 100 FREQUENCY (MHz) 1000 2000 85C 25C -20 -40C -30 -40 -50 -60 -70 ENABLE=HI 0
LNA S12 vs Frequency
LNA S22 vs Frequency and Temperature
0 -2 -4 -6 Sii MAGNITUDE (dB) -8 -10 85C -12 -14 -16 -18 -20 800 900 1000 1100 FREQUENCY (MHz) 1200 -40C -18 -20 800 25C -16 0 -2 -4 -6 -8 -10 -12 -14
LNA Thru S11 and S22 vs Frequency
S22 MAGNITUDE (dB)
S22
S11
900
1000 FREQUENCY (MHz)
1100
1200
SR00086
Figure 5. LNA S11/S12/S22 Performance Characteristics
Table 1.
Freq. MHz 800 900 1000 1100 1200
S-Parameters
S11 -9.5 -9.5 -9.4 -9.1 -8.9 -160 -172 -173 -200 -216 -46 -43 -40 -37 -35 S12 8 19 17 12 1 17.9 16.4 15.1 13.8 12.9 S21 125 105 88 70 55 -18.0 -15.8 -14.0 -12.4 -11.1 S22 151 122 98 77 58
1993 Dec 15
52
Philips Semiconductors
Product specification
1GHz LNA and mixer
NE/SA600
LNA OVERLOAD/NOISE/DISTORTION CHARACTERISTICS
4.5V VCC = VCCMX 5.5V, Test Fig. 1, unless otherwise specified. LNA Input 1dB Gain Compression Point vs Frequency
0
LNA Input 1dB Gain Compression Point vs Temperature
0
-5
-5
-10 P-1 (dBm) P-1 (dBm) 800 900 1000 1100 FREQUENCY (MHz) 1200
-10
-15
-15
-20
-20
-25
-25
-30
-30 -40 -20 0 20 40 60 TEMPERATURE (C) 80 100
LNA 50 Noise Figure vs Frequency
3 3
LNA 50 Noise Figure vs Temperature
2.5
2.5
2
2
NF (dB)
1.5
NF (dB)
1.5
1
1 F = 900MHz
0.5
0.5
0 800 900 1000 FREQUENCY (MHz) 1100 1200
0 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
LNA Input Third-Order Intercept vs Frequency
0 TEST FIGURE 2 -2 -4 -6 IP3 (dBm) -8 IP3 (dBm) -10 -12 -14 F2 = F1 + 100kHz -16 -18 -20 800 900 1000 1100 FREQUENCY (MHz) 1200
LNA Input Third-Order Intercept vs Temperature
0 TEST FIGURE 2 -2 -4 -6 -8 -10 -12 -14 -16 -18 -20 -40 -20 0 20 40 60 TEMPERATURE (C) 80 100 F1 = 900MHz F2 = 900.1MHz
SR00087
Figure 6. LNA Overload/Noise/Distortion Performance Characteristics 1993 Dec 15 53
Philips Semiconductors
Product specification
1GHz LNA and mixer
NE/SA600
MIXER GAIN/NOISE CHARACTERISTICS 4.5V VCC = VCCMX 5.5V, Test Figure 1, unless otherwise specified.
Mixer Voltage Conversion Gain vs LO Power
12
Mixer Voltage Conversion Gain vs IF Frequency
12
10 VOLTAGE CONVERSION GAIN (dB) VOLTAGE CONVERSION GAIN (dB)
10
8
8
6 Frf = 900MHz Flo = 1GHz Fif = 100MHz Scaled to RL1 = RL2 = 1k
6 Frf = 900MHz Flo > Frf Plo = 0dBm Scaled to RL1 = RL2 = 1k
4
4
2
2
0 -10
0 -8 -6 -4 -2 0 LO POWER (dBm) 2 4 6 0 50 100 150 200 250 300 IF FREQUENCY (MHz)
Mixer Voltage Conversion Gain vs Temperature
12 24
Mixer 50 Noise Figure vs LO Power
TEST FIGURE 3 22
10 20 VOLTAGE CONVERSION GAIN (dB) 8 NOISE FIGURE (dB) 18 16 14 12 10 8 0 -40 -20 0 20 40 60 TEMPERATURE (C) 80 100 6 -12 -10 -8 -6 -4 -2 0 LO POWER (dBm) 2 4 6 Frf = 881MHz Plo = 981MHz Fif = 100MHz
6 Frf = 900MHz Flo = 1GHz Fif = 100MHz Plo = 0dBm Scaled to RL1 = RL2 = 1k
4
2
Mixer Noise Figure vs IF Frequency
24 TEST FIGURE 3 22 20 18 16 14 12 10 8 6 50 60 70 80 90 100 110 120 IF FREQUENCY (MHz) NOISE FIGURE (dB) 22 20 18 16 14 12 10 8 6 -40 24
Mixer Noise Figure vs Temperature
TEST FIGURE 3
NOISE FIGURE (dB)
Frf = 881MHz Flo > Frf Plo = 0dBm IF Tuned to 81MHz
Frf = 881MHz Flo = 981MHz Fif = 100MHz Plo = 0dBm
-20
0
20 40 60 TEMPERATURE (C)
80
100 SR00088
Figure 7. Mixer Gain/Noise Performance Characteristics
1993 Dec 15
54
Philips Semiconductors
Product specification
1GHz LNA and mixer
NE/SA600
MIXER OVERLOAD/DISTORTION CHARACTERISTICS 4.5 VCC = VCCMX 5.5V, Test Fig. 1, unless otherwise specified
Mixer Input 1dB Gain Compression Point vs LO Power
0 TEST FIGURE 2 -1 -2 -3 -4 P-1 (dBm) P-1 (dBm) -5 -6 -7 -8 -9 -10 -10 -8 -6 -4 -2 0 2 4 6 LO POWER (dBm) Frf = 900MHz Plo = 1GHz Fif = 100MHz -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) Frf = 900MHz Flo = 1GHz Fif = 100MHz Plo = 0dBm
Mixer Input 1dB Gain Compression Point vs Temperature
0 TEST FIGURE 2
Mixer Input Third-Order Intercept Point vs LO Power
10 9 8 7 6 IP3 (dBm) 5 4 3 2 1 0 -10 Frf1 = 900MHz Frf2 = 901MHz Flo = 1GHz Fif = 100MHz
Mixer Input Third-Order Intercept Point vs IF Frequency
10 9 8 7 6 IP3 (dBm) 5 4 3 2 1 0 Frf1 = 900MHz Frf2 = 901MHz Flo > Frf
-8
-6
-4 -2 0 LO POWER (dBm)
2
4
6
50
75
100
125
150
175
200
IF FREQUENCY (MHz)
Mixer Input Third-Order Intercept Point vs RF Frequency
10 9 8 7 6 IP3 (dBm)
Mixer Input Third-Order Intercept Point vs Temperature
10 9 8 7 6 IP3 (dBm) 5 4 3
5 4 3 2 1 0 800 900 1000 FREQUENCY (MHz) 1100 1200 Frf1 = X00MHz Frf2 = X01MHz X = 8, 9, 10, 11, 12 Flo > Frf Fif = 100MHz
2 1 0 -40
Frf1 = 900MHz Frf2 = 901MHz Flo = 1GHz Plo = 0dBm Fif = 100MHz -20 0 20 40 60 TEMPERATURE (C) 80 100
SR00089
Figure 8. Mixer Overload/Distortion Characteristics
1993 Dec 15
55
Philips Semiconductors
Product specification
1GHz LNA and mixer
NE/SA600
MIXER S11/ISOLATION/INTERFERENCE CHARACTERISTICS
4.5 VCC = VCCMX 5.5V, Test Fig. 1, unless otherwise specified Mixer S11 at RF Port vs Frequency and Temperature
0 -5 -5 -10 -15 -20 -25 25C -30 -35 -40 800 900 1000 1100 1200 FREQUENCY (MHz) S11 MAGNITUDE (dB) 0
Mixer S11 at LO Port vs Frequency and Temperature
S11 MAGNITUDE (dB)
-10 -40C -15 25C
-40C
-20 85C -25 800 900 1000 FREQUENCY (MHz) 1100 1200 85C
Mixer Output Interferring Signal vs Input Interferring Signal Strength
OUTPUT INTERF. SIGNAL REL. TO OUTPUT SIGNAL (dB) 0 0
Conversion Gain Variation vs RF Signal Overdrive
-10 CHANGE IN CONVERSION GAIN
-5
-20
-10
-30
-15
-40 Frf = 900MHz Frf-interf = 901MHz Flo = 1GHz Plo = 0dBm Fif = 100MHz Fif-interf = 98MHz
-20 Frf = 900MHz Flo = 1GHz Plo = 0dBm Fif = 100MHz
-50
-25
-60
-30
-70 -30 -25 -20 -15 -10 -5 0 5 10 INPUT INTERFERRING SIGNAL (dBm)
-35 -20 -15 -10 -5 0 5 10 15 20 RF SIGNAL POWER
SR00090
Figure 9. Mixer S11/Isolation/Interference Characteristics
1993 Dec 15
56
Philips Semiconductors
Product specification
1GHz LNA and mixer
NE/SA600
OVERALL PERFORMANCE: ISOLATION CHARACTERISTICS
4.5 VCC = VCCMX 5.5V, Test Fig. 1, unless otherwise specified Isolation From LNA Output to Mixer RF Input vs Frequency
0 0
Isolation From LO vs Frequency
-10 ISOLATION MAGNITUDE (dB) ISOLATION MAGNITUDE (dB)
-10
-20
-20
At LNA input - ENABLE = LO -30 At Mixer RF input
-30
ENABLE=LO
-40
ENABLE=HI
-40 At LNA input - ENABLE = HI -50
-50
-60 800 900 1000 1100 FREQUENCY (MHz) 1200
-60 800 900 1000 1100 1200 FREQUENCY (MHz)
SR00091
Figure 10. Overall Performance: Isolation Characteristics
SPECIFICATIONS
The goal of the Specifications section of the datasheet is to provide information on the NE/SA600 in such a way that the designer can estimate statistical variations, and can reproduce the measurements. To this end the high frequency measurements are specified with a particular PC board layout. Variations in board layout will cause parameter variations (sensitive parameters are discussed in the sections on the LNA and mixer below). For many RF parameters the 3 sigma limits are specified. Statistically only 0.26% of the units will be outside these limits. The LNA + mixer conversion gain is measured with an incident 900MHz signal and a 83MHZ SAW filter at the IF output. This measurement along with a gain measurement of the LNA ensure the correct operation of the chip and also allows a calculation of mixer conversion gain.
LOIN Mixer LO port, AC coupling required, DC=3.35V, frequency range from 100MHz to 2.5GHz, impedance close to 50 resistive. IFOUT Mixer IF port, open-collector output with 1.6mA DC, frequency range DC to 1GHz, impedance approximately 1pF capacitive. Enable TTL/CMOS compatible input. Bias current approximately zero.
CONVERSION GAIN DEFINITIONS
Referring to the figure above, we define the ratio of VA (at the IF frequency) to VI (at the RF frequency) to be the Available Voltage Conversion Gain, or more simply Voltage Conversion Gain,
PIN DESCRIPTIONS AND OPERATIONAL LIMITS
RFINA Input of LNA, AC coupling required, DC = 0.78V, frequency range from DC to 2GHz, gain at low frequencies is 40dB -- so be careful of overload, impedance below 50, shunt 15-18nH inductor helps input match and noise figure. RFOUTA Output of LNA, AC coupling required, DC = 1.27V, frequency range from DC to 2GHz, impedance above 50. BYPASS Bypass capacitor should be 100 times larger than the largest signal coupling capacitor for the LNA, DC = 1.05V. RFINMX Mixer RF port, AC coupling required, DC = 1.43V, frequency range from 100MHz to 2.5GHz, impedance close to 50 resistive. 1993 Dec 15 57
10H RL1 IF FILTER VO VA 1k LO VI RL2
RF
SR00092
Figure 11. VG C + 20 log VA VI
where VA and VI are expressed in similar voltage units (such as peak-to-peak). The voltage output VA is decreased by the IF Filter
Philips Semiconductors
Product specification
1GHz LNA and mixer
NE/SA600
loss (and any other matching required). Typically, VGC is 10.4dB for the NE/SA600 mixer with the net IF impedance equal to 500. It is more common to express the conversion gain in terms of power, so we have the Power Conversion Gain, P PG C + 10 log A * 3dB PI where PA = VA2 / RIF and PI = VI2 / RRF. RIF is the net resistance at the IF frequency at the IF port, and RRF is the input impedance at the mixer RF port. With a 500 IF impedance and a 50 RF input impedance, the conversion gain works out to -2.6dB typically. The power delivered to the load is down 3dB with respect to the available power because of loss in RL1.
draw is 9.8mA while enable is high (1mA powered down). The Pin 14 VCCMX powers the mixer and typically has 3.2mA of current (assuming an inductor biasing the IFout back to VCCMX). Care must be taken to avoid bringing any IC pin above VCC by more than 0.3V, or below any ground by more than 0.3V. For example, this can occur if the enable pin is fed from a microcontroller that is powered up quicker than the NE/SA600. In this condition the internal electrostatic discharge (ESD) protection network may turn-on, possibly causing a part misfunction. Generally this condition is reversible, so long as the source creating the overstress is current limited to less than 100mA. To avoid the problem, make sure both VCC pins are tied together near the IC, and install a 1k resistor in series with the enable pin if it is likely to go above VCC.
THEORY OF OPERATION
The NE/SA600 is fabricated on the Philips Semiconductors advanced QUBiC technology that features 1m channel length MOSFETs and 13GHz FT bipolar transistors. LNA The Low Noise Amplifier (LNA) is a two stage design incorporating feedback to stablize the amplifier. An external bypass capacitor of (typically) 0.01F is used. The inputs and outputs are matched to 50. The amplifier has two gain states: when the ENABLE pin is taken high, the amplifier draws 9mA of current and has 16dB of gain at 900MHz. When the ENABLE pin is low, the amplifier current goes to zero, and the amplifier is replaced by a thru. Typical loss for the thru is 7dB. This dual-gain state approach can be used in bang-bang control systems to achieve a low gain, high overload front-end as well as the more usual high gain, low overload front-end. The amplifier has gain to frequencies past 2GHz, but a practical upper end is 1.6-1.7GHz. Both the input match and the noise figure (NF) can be improved with a shunt 15-18nH inductor at the input. Typically, the gain increases 0.4dB, the match improves to 13-16dB, and the noise figure drops to 1.95-2dB. Variations of any of the RF parameters with VCC is negliglible, and variation with temperature is minimal. Mixer The mixer is a single-balanced topology designed to draw very low current, typically 4mA, and provide a very high input third-order intermodulation intercept point , typically IP3=+6dBm. The RF and LO ports impedances are nearly 50 resistive, and the IF output is an open collector. The open-collector output allows direct interfacing with high impedance IF filters, such as surface acoustic wave (SAW) filters without the need for external step-up transformers (which are needed for 50 output mixers). The basic mixer is functional from DC to well over 2.5GHz, but RF and LO return losses degrade below 100MHz. The IF output can be used from DC to 500MHz or more, although typically the intermediate frequency is in the range 45-120MHz in many 900MHz receivers. To achieve the lowest noise, the LO drive level should be increased as high as possible, consistent with power dissipation limitations.
BOARD LAYOUT CONSIDERATIONS
The LNA is sensitive to mutual inductance from the input to ground. Therefore long narrow input traces will degrade the input match. Ideally, a top side ground-plane should be employed to maximize LNA gain and minimize stray coupling (such as LO to antenna). To avoid amplifier peaking, the output and input grounds should not be run together. Attach both grounds to a solid ground plane. A solid ground plane beneath the package will maximize gain. Top side to back side ground through holes are highly recommended. The mixer is relatively insensitive to grounding. Care should be taken to minimize the capacitance on the RF port (Pin 11) for best noise figure. Also, the capacitance on the IFout pin must be kept small to avoid conversion gain rolloff when using high IF frequencies. The purpose of the inductor from IFout to VCC is to set the midpoint of the IF swing to be VCC. Without this inductor the part is sensitive to output overload under low VCC (VCC = 4.5V) and hot temperature conditions. The VCCMX pin must be kept at the same potential as the VCC pin.
APPLICATIONS INFORMATION
The NE/SA600 is a high performance, wide-band, low power, low noise amplifier (LNA) and mixer circuit integrated in a BiCMOS technology. It is ideally suited for RF receiver front-ends for both analog and digital communications systems. There are several advantages to using the NE/SA600 as a high frequency front-end block instead of a discrete implementation. First is the simplicity of use. The NE/SA600 does not need any external biasing components. Due to the higher level of integration and small footprint (SO14) package it occupies less space on the printed circuit board and reduces the manufacturing cost of the system. Also the higher level of integration improves the reliability of the LNA and mixer over a discrete implementation with several components. The LNA thru mode in NE/SA600 helps reduce power consumption in applications where the amplifiers can be disabled due to higher received signal strength (RSSI). Other advantages of this feature are described later in this section. The mixer is an active mixer with excellent conversion gain at low LO input levels, so LO levels as low as -5dBm to -10dBm can be used depending on the applications requirement for mixer gain, mixer noise figure and mixer third order intercept point. This reduces the LO drive requirements from the VCO buffer, thus reducing its current consumption. Also, due to lower LO levels, the shielding requirements can be minimized or eliminated, resulting in substantial cost savings and weight and space reduction.
POWER SUPPLY ISSUES
VCC bypassing is important, but not extremely critical because of the internal supply regulation of the NE/SA600. The Pin 1 VCC supplies the LNA and powers overhead circuitry. Typical current
1993 Dec 15
58
Philips Semiconductors
Product specification
1GHz LNA and mixer
NE/SA600
And last but not least, is the impedance matching at LNA inputs and outputs and mixer RF and LO input ports. Only those who have toiled through discrete transistor implementations for 50 input and output impedance matching can truly appreciate the elegance and simplicity of the NE/SA600 input and output impedance matching to 50. Also, the mixer output impedance is high, so matching to a crystal or SAW IF filter becomes extremely easy without the need for additional IF impedance transformers (tapped-C networks with inductors or baluns). The NE/SA600 applications and demo board features standard low cost 62mil FR-4 board. A top-side ground plane is used and 50 coplanar transmission lines are used. LO and RFINA traces are perpendicular. Provisions for the image reject filter between RFOUTA and RFINMX are provided. A simple LC match for 80MHz IF is used so that 50 measurements can be made on the demo board. The NE/SA600 applications evaluation board schematic is shown in Figure 1. The VCC (Pin 1) and VCCMX (Pin 14) are tied together and the power supply is bypassed with capacitors C5 and C6. These capacitors should be placed as close to the device as practically possible. C1 is the DC blocking capacitor to the input of the LNA. L1 provides additional input matching to the LNA for an improved return loss (S11). This inductor can be a surface-mount component or can be easily drawn on the printed circuit board (small spiral or serpentine). This additional match improves the gain of the LNA by 0.4dB and lowers the noise figure to 2dB or less. If the typical gain of the LNA of 16dB is acceptable with 2.2dB of noise figure, then L1 can be eliminated. If the LNA input is fed from a duplexer or selectivity filter after the antenna, C1 can also be eliminated since the filter will also provide DC blocking. The LNA bypass capacitor C3 should be at least 100 times C1 or C9 for low frequency stability. Switch S1 toggles the LNA gain/through function. R1 is used only to limit the maximum current into the enable pin and only necessary if enable may power up before the VCC. C4 is a DC blocking capacitor for the LO input pin and may not be needed in actual applications if the VCO output is isolated and will not upset the internal DC biasing of the mixer. The image reject filter goes between the output of the LNA and the RF input to the mixer. Since the LO input, RF output and mixer input are all 50 matched impedances internally, there is no need for any external components. C8 and C9 are DC blocking capacitors to the connectors and will not be needed in an actual application. R2 and L2 are the load to the mixer output which is typical of the IF crystal or SAW filters. C2 and L3 provide a match from the high impedance mixer output to a 50 test set-up (spectrum analyzer, etc.) and C7 is a DC blocking capacitor for the mixer output. The printed circuit board layout for the schematic of Figure 1 is shown in Figure 14. It is a very simple printed circuit board layout with all the components on a single side. The layout also accomodates a two pole image reject filter between the LNA outupt and mixer input. All the input and output traces to the LNA and mixer should be 50 tracks with the exception of mixer output, which can be very narrow due to the higher impedances of the filter. The NE/SA600 internal supply is very well regulated. This is seen from Figure 15 which shows the ICC vs. VCC for the NE/SA600. Table NO TAG shows the S11, S21, S22 and S21 for the LNA from 800-1200MHz. Typical measurements at 900MHz for the critical parameters such as gain, noise figure, IP3, 1dB compression point, etc. as measured on an applications evaluation board are as follows :
LNA gain = 16.5dB LNA through = -7dB Mixer gain =-3dB (into a 50 load) LNA noise figure = 2dB Mixer noise figure = 14dB LNA IP3 = -10dBm (in gain mode) LNA IP3 = +26dBm (in through mode) LNA 1dB compression point = -20dBm Mixer 1dB compression point = -4dBm The shunt inductor L1 for input match is optional. Figure 16 shows the effect of the inductor value from 8.2nH to 15nH on gain, noise figure and input match. The total power gain for the LNA and mixer (excluding the image reject filter) in a system where the output of the mixer is loaded with 50 is about 14dB. In an actual system the output impedance of the mixer is usually much higher than 50 (more like 1k or higher) and so it is more important to consider the voltage gain from the input at the LNA to the mixer output. The voltage gain in this case will be about 29.85V/V. The total noise figure for the LNA and mixer combination is be about 3.27dB. The input third order intercept point for the LNA and mixer is about -11dBm. In the LNA through mode, the intercept point for the combination is higher than +19dBm. This LNA through feature provides an additional boost to the total dynamic range of the system. The NE/SA600 finds applications in many areas of RF communications. It is an ideal down converter block for high performance, low cost, low power RF communications transceivers. The front-end of a typical AMPS/TACS/NMT/TDMA/CDMA cellular phone is shown in Figure 13. This could also be the front-end of a VHF/UHF handheld transceiver, UHF cordless telephone or a spread spectrum system. The antenna is connected to the duplexer input. The receiver output of the duplexer is connected to the RF input of the LNA. If the additional improvement in noise figure and gain are not needed to meet the system specifications then L1 and C1 can be eliminated. In TDMA systems, the NE/SA600 can be totally powered down by Q1 and the two resistors. In this mode the current consumption will be zero mA. Care should be taken in the software of the system to insure that the enable pin on NE/SA600 tied to the LNA gain control port is held low while the device is in total power down mode. L2 and C2 can be tuned to the IF frequency and to match to the IF filter impedance. A complete analysis of the front-end shows that the total voltage gain from the antenna input to the mixer output is about 9.5V/V. This value includes a 3.2dB loss for the duplexer and a 1.8dB loss for the bandpass filter. The noise figure as referred to the antenna is 7dB and the input third order intercept point is about -7.5dBm. In LNA through mode the input third order intercept point increases to about +24dBm. During normal operation of a handheld RF receiver the received signal strength (RSSI) is nominally greater than -100dBm. The signal only drops below this level due to severe multipath fading, shadow effect or when the receiver is at extreme fringes of cell coverage. The LNA through mode can be used here as a two step gain control such that when RSSI is below a certain threshold level (e.g. -90dBm), the LNA has a -7dB loss and the total current consumption of the NE/SA600 is only 4.3mA. The sensitivity of the system will not suffer because the received RF signal is much higher than the noise floor of the system. When the RSSI falls below a certain threshold (e.g. -95dBm) the LNA is enabled to give the full
1993 Dec 15
59
Philips Semiconductors
Product specification
1GHz LNA and mixer
NE/SA600
16.5dB of gain with 2dB of noise figure. In this mode the current consumption is increased to 13mA. But for hand-held equipment, the average current consumption will be closer to 5-6mA. The other advantage of the LNA through mode besides power savings is the input overload characteristics. Due to the much higher input third order intercept point of the LNA (+26dBm), the receiver is immune to strong adjacent channel interference. Implementing this feature with an FM/IF device such as the NE625/7 with fast RSSI response and a window comparator toggling the LNA mode of NE/SA600, a fast two-step AGC with response time less than 10s can be achieved.
This is a very useful feature to equalize multipath fading effects in a mobile radio system. In conclusion, the NE/SA600 offers higher level of integration, higher reliability, higher level of performance, ease of use, simpler system design at a cost lower than the discrete multi-transistor implementations. In addition, the NE/SA600 provides unique features to enhance receiver performance which are almost unattainable with discrete implementations.
VCC
C6 10nF R2 1k C2 4.7pF
C5 0.1F 1V C VCCMX 14 IFOUT 13 GNDMX 12
L2 10H
C7 10nF
L3 470nH
IF OUT
C
2 GNDB RF INPUT 900MHz C1 3 RF INA 100pF L1 15nH BYPASS C3 10nF 4 GND A1 5 BYPASS 6 GNDLO 7 LOIN RF INMX 11
C8 100pF GNDA2 10 RF OUTA 9 ENABLE 8 100pF BANDPASS FILTER
MIXER IN
IN
OUT
C9
RF OUT
C4 100pF
NE/SA600
S1
LO INPUT R1 1k
VCC
SR00093
Figure 12.
1993 Dec 15
60
Philips Semiconductors
Product specification
1GHz LNA and mixer
NE/SA600
POWER DOWN VCC Q1 BCX17 15k 5.1k from Power Amp ANTENNA 1 C4 0.1F DUPLEXER 1V C VCCMX 14 C2 IFOUT 13 GNDMX 12 RF INMX 11 GNDA2 10 RF OUTA 9 ENABLE 8 BANDPASS FILTER L2 1 I G 2 IF FILTER O 3 To FM-IF Circuits NE605/6/7/8 C5 10nF
2
C
2 GNDB C1 3 100pF L1 15nH C3 10nF 4 GND A1 5 BYPASS 6 GNDLO 7 LOIN 3 RF INA
IN
OUT
NE/SA600
from VCO/Synthesizer UMA1014 R1 1k
LNA GAIN CONTROL
SR00094
Figure 13.
1993 Dec 15
61
Philips Semiconductors
Product specification
1GHz LNA and mixer
NE/SA600
SILKSCREEN
TOP
BOTTOM
SR00095
Figure 14. PC Board Layout
1993 Dec 15
62
Philips Semiconductors
Product specification
1GHz LNA and mixer
NE/SA600
Total Supply Current vs Temperature
16 ENABLE=HI 14 12 10 I CC (mA) 8 6 4 ENABLE=LO 2 0 -40 2 0 -20 0 20 40 60 TEMPERATURE (C) 80 100 4.5 14 12 10 8 6 4 16
Total Supply Current vs VCC
ENABLE=HI
I CC (mA)
ENABLE=LO
4.75
5 VCC (V)
5.25
5.5
SR00096
Figure 15.
LNA Noise Figure vs. Frequency and Shunt Inductance
3 2.8 0nH 2.6 18 2.4 S21 MAGNITUDE (dB) 2.2 2 15nH 1.8 1.6 14 1.4 13 1.2 1 700 800 900 FREQUENCY (MHz) 1000 1100 12 700 8.2nH 17 20 15nH
LNA Gain vs. Frequency and Shunt Inductance
8.2nH
19
NF (dB)
0nH 16
15
800
900 FREQUENCY (MHz)
1000
1100
SR00097
Figure 16.
1993 Dec 15
63

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