View SA637DK_770676.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

Philips Semiconductors RF Communications Products
Product specification
Low-voltage digital IF receiver
SA637
DESCRIPTION
The SA637 is a low-voltage high performance monolithic digital system with high-speed RSSI incorporating a mixer, oscillator with buffered output, two limiting intermediate frequency amplifiers, fast logarithmic received signal strength indicator (RSSI), voltage regulator, RSSI op amp and power down pin. The SA637 is available in SSOP (shrink small outline package). The SA637 was designed for portable digital communication applications and will function down to 2.7V. The limiter amplifier has differential outputs with 2MHz small signal bandwidth. The RSSI output has access to the feedback pin. This enables the designer to level adjust the outputs or add filtering.
FEATURES
* VCC = 2.7 to 5.5V * Low power receiver (3.8mA @ 3V) * Power down mode (ICC = 110A) * Fast RSSI rise and fall times * Extended RSSI range with temperature
compensation
PIN CONFIGURATION
DK Packages
RFIN 1 RFIN 2 OSC E 3 OSC B 4 OSC 5 BUFFER 6 V 20 MIXER OUTPUT 19 IF AMP DECOUP 18 IF AMP IN 17 IF AMP DECOUP 16 IF AMP OUT 15 GND 14 LIMITER IN 13 LIMITER DECOUP 12 LIMITER DECOUP 11 LIM OUT (+)
* RSSI op amp * 2MHz limiter small signal bandwidth * 455kHz filter matching (1.5k) * Differential limiter output * Oscillator buffer * SSOP-20 package
APPLICATIONS
CC
RSSI 7 RSSI 8 FEEDBACK POWER 9 DOWN LIM OUT (-) 10
* ADC (American Digital Cellular) * Digital receiver systems * Cellular radio
ORDERING INFORMATION
DESCRIPTION 20-Pin Plastic Shrink Small Outline Package (Surface-mount) TEMPERATURE RANGE -40 to +85C ORDER CODE SA637DK DWG # 1563
BLOCK DIAGRAM
20 19 18 17 16 15 14 13 12 11
GND IF AMP MIXER
LIMITER
OSCILLATOR
FAST RSSI
+- + - E 1 2 3 4 B 5 VCC 6 7 8
POWER DOWN
9
10
October 27, 1993
2
853-1718 11205
Philips Semiconductors RF Communications Products
Product specification
Low-voltage digital IF receiver
SA637
ABSOLUTE MAXIMUM RATINGS
SYMBOL VCC VIN TSTG TA Supply voltage Voltage applied to any other pin Storage temperature range Operating ambient temperature range PARAMETER RATING -0.3 to +6.0 -0.3 to (VCC + 0.3) -65 to +150 -40 to +85 UNITS V V
C C
NOTE: Thermal impedance (JA) = 117C/W
DC ELECTRICAL CHARACTERISTICS
VCC = +3V, TA = 25C; unless otherwise stated. SYMBOL VCC ICC PARAMETER Power supply voltage range DC current drain Standby Input current Input level tON tOFF Power up time Power down time Pin 9 = HIGH or OPEN VCC = 4.7V Pin 9 = LOW Pin 9 = LOW Pin 9 = HIGH Pin 9 = LOW Pin 9 = HIGH RSSI valid (10% to 90%) RSSI invalid (90% to 10%) -10 -10 0 0.7VCC 10 5 TEST CONDITIONS MIN 2.7 3.8 4.4 0.11 LIMITS TYP MAX 5.5 4.5 5.5 0.5 10 10 0.3VCC VCC V mA mA mA A A A A s s UNITS
AC ELECTRICAL CHARACTERISTICS
TA = 25C; VCC = +3V, unless otherwise stated. RF frequency = 90MHz; RF input step-up = +14.5dBV; IF frequency = 455kHz; RF level = -68dBm. Test circuit Figure 1. The parameters listed below are tested using automatic test equipment to assure consistent electrical characteristics. The limits do not represent the ultimate performance limits of the device. Use of an optimized RF layout will improve many of the listed parameters. SYMBOL Mixer/Osc section fIN fOSC NF TOI P1dB RIN CIN ROUT IF section IF amp power gain Limiter power gain IFBW IF amp bandwidth 50 source 50 source 36 60 2.5 dB dB MHz Input signal frequency Crystal oscillator frequency Noise figure at 90MHz Third-order input intercept point Input 1dB compression point Conversion power gain Mixer input resistance Mixer input capacitance Mixer output resistance Buffered LO output level LO = 447mVP-P, 1k AC load 100 Matched 50 Matched input and output Input matched to 50 source 200 200 6.2 -17 -27 7 2.5 2.2 1.87 300 500 MHz MHz dB dBm dBm dB k pF k mVP-P PARAMETER TEST CONDITIONS MIN LIMITS TYP MAX UNITS
October 27, 1993
3
Philips Semiconductors RF Communications Products
Product specification
Low-voltage digital IF receiver
SA637
AC ELECTRICAL CHARACTERISTICS (Continued)
SYMBOL PARAMETER RF RSSI output TEST CONDITIONS MIN RF level = -118dBm RF level = -68dBm RF level = -28dBm RSSI range RSSI accuracy RSSI ripple RSSI speed Rise time RSSI speed Fall time IF input impedance IF output impedance Limiter input impedance Limiter output impedance Limiter output signal level Limiter output DC level Differential output matching Differential output offset (Pin 10, Pin 11) (Pin 10, Pin 11) 1.5k AC load No interstage filter With interstage filter 10 50 1.5 1.5 1.5 200 280 1.27 6 30 overall bandwidth is limited to 2MHz. The input and output impedance of the IF amplifier and the input impedance of the IF limiter are set to 1500 (match to 455kHz filter). A second filter is connected between the IF amplifier and the limiter for improved channel selectivity and reduced instability. This ceramic filter provides 3dB interstage insertion loss which results in optimal RSSI linearity. The overall gain can be reduced if desired by adding an external attenuator after the IF amplifier. The differential limiter outputs (Pins 10 and 11) are available for demodulator circuits. s s k k k mVP-P V mV mV No interstage filter With interstage filter 2.5 22 s s .01 .4 1.0 LIMITS TYP 0.2 0.9 1.7 90 1.5 30 MAX .65 1.7 2.3 V V V dB dB mVP-P UNITS
CIRCUIT DESCRIPTION Mixer
The mixer has a balanced input and is capable of being driven single-ended. The input impedance is 2.5k in parallel with a 2.2pF cap at 90MHz RF. The mixer output can drive a 1500 ceramic filter at 455kHz or 600kHz directly without any matching required. The mixer conversion power gain is 7dB when both input and output are matched and optimum LO level is used to drive the internal mixer core.
bandwidth of the external bandpass filter that is placed between the mixer and the IF, and the external filter placed between the IF amplifier and limiter. Since the RSSI function requires the signal to propagate through the whole IF strip, and the rise and fall time of the filters are inversely proportional to their bandwidth, there is a trade-off between channel selectivity and RSSI response. A possible solution is to use a second SA637 with wider band external filters for faster RSSI response. The RSSI curve is temperature compensated and in addition is designed for improved consistency from unit to unit. The RSSI circuit drives an on-chip low power op amp with rail-to-rail output which can be connected as a unity gain RSSI buffer or a gain stage or even a comparator.
Oscillator and Buffer
The on-board oscillator supplies the signal for the mixer down-conversion. The internally biased transistor can be configured as a Colpitts or Butler overtone crystal oscillator. The transistor's bias current can be increased if desired by adding a shunt resistor from Pin 3 to ground. The oscillator's buffered output (Pin 5) can be used as a feedback signal to lock the oscillator to an appropriate reference.
RSSI
The received signal strength indicator provides a linear voltage indication of the received signal strength in dB for a range in excess of 90dB. The response time to a change in input signal is less than a few microseconds and the delay is kept to a minimum because of the use of a minimum phase shift circuit. Because of the speed of the RSSI circuit, the RSSI rise and fall time may, in practice, be dominated by the
DC Power Supply
The IC is designed for operation between 2.7 and 5.5V. A power supply dependent biasing scheme is used in the mixers to benefit from the large headroom available at higher VCCs.
IF Amplifier and IF Limiter
The IF strip provides more than 95dB of power gain for the down converted signal. Its
October 27, 1993
4
Philips Semiconductors RF Communications Products
Product specification
Low-voltage digital IF receiver
SA637
PERFORMANCE CHARACTERISTICS
Supply Current vs Temperature and Supply Voltage
8.00 POWER DOWN SUPPLY CURRENT (mA) 7.00 SUPPLY CURRENT (mA) 6.00 5.00 4.00 2.7V 3.00 2.00 1.00 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 TEMPERATURE (C) 5.5V 3V 0.50 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.00 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 3V 2.7V 5.5V
Power Down Supply Current vs Temperature and Supply Voltage
TEMPERATURE (C)
Mixer Power Gain vs Temperature and Supply Voltage
10.00 THIRD-ORDER INTERCEPT POINT (dBm) 9.00 MIXER GAIN (dB) 8.00 5.5V 7.00 3V 6.00 5.00 4.00 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 TEMPERATURE (C) 2.7V -10.00 -12.00 -14.00 -16.00
Mixer Third Order Input Intercept Point vs Temperature and Supply Voltage
5.5V 3V 2.7V
-18.00 -20.00 -22.00 -24.00 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90
TEMPERATURE (C)
Oscillator Buffer Output Level vs Temperature and Supply Voltage
0.50 0.45 0.40 OUTPUT POWER (dBm) MIXER GAIN (dB) 5.5V 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.00 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 2.7V 3V 0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -50
Mixer Third Order Intercept and Compression vs Input Power - Vcc=3V, T=25C
-45
-40
-35
-30
-25
-20
-15
-10
TEMPERATURE (C)
INPUT POWER (dBm)
October 27, 1993
5
Philips Semiconductors RF Communications Products
Product specification
Low-voltage digital IF receiver
SA637
PERFORMANCE CHARACTERISTICS (cont.)
IF Power Gain vs Temperature and Supply Voltage
40.00
Limiter Power Gain vs Temperature and Supply Voltage
65.00
38.00 IF GAIN (dB)
5.5V 3V IF GAIN (dB)
63.00 5.5V 61.00 3V 2.7V 59.00
36.00
2.7V
34.00
32.00
57.00
30.00 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 TEMPERATURE (C)
55.00 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 TEMPERATURE (C)
Limiter Output (+) Level vs Temperature and Supply Voltage
400.00 5.5V 350.00 LIMITER OUTPUT (+) (mVp-p) 300.00 250.00 200.00 150.00 100.00 50.00 0.00 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 TEMPERATURE (C) 2.7V LIMITER OUTPUT (-) (mVp-p) 3V 350.00 300.00 250.00 200.00 150.00 100.00 50.00 0.00 400.00
Limiter Output (-) Level vs Temperature and Supply Voltage
5.5V 3V 2.7V
-50 -40 -30 -20 -10
0
10
20
30 40
50
60
70
80
90
TEMPERATURE (C)
RSSI vs RF Level and Temperature - VCC = 3V
2.50 2.25 2.00 1.75 RSSI (V) 1.50 1.25 1.00 0.75 0.50 0.25 0.00 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 -40C +85C RSSI (V) 2.50
RSSI vs RF Level and Supply Voltage - Temperature = 25C
5.5V 2.25 2.00 1.75 1.50 1.25 1.00 0.75 0.50 0.25 0.00 -120 -110 -100 -90 -80 -70 -60 -50 -40 -30 -20 -10 0 2.7V 3V
RF LEVEL (dBm)
RF LEVEL (dBm)
October 27, 1993
6
Philips Semiconductors RF Communications Products
Product specification
Low-voltage digital IF receiver
SA637
PIN FUNCTIONS
PIN PIN DC V No. MNEMONIC EQUIVALENT CIRCUIT PIN PIN DC V No. MNEMONIC EQUIVALENT CIRCUIT
1
RF IN
+1.40 6
2.5k 1 2.5k 2
6
VREF
VCC
+3.00
BANDGAP
RF 2 BYPASS +1.40
VCC
RSSI 7 OSC 3 E +1.79
4 MIX
OUT
+0.20
+ --
7
18k
VCC 3
OSC 4 B +2.56
150A
RSSI 8 FEEDBACK +0.20
8
--
+
OSC 5 BUFFER +1.79
R
POWER 9
5 150A
DOWN
+2.00
9
R
October 27, 1993
7
Philips Semiconductors RF Communications Products
Product specification
Low-voltage digital IF receiver
SA637
PIN FUNCTIONS (continued)
PIN PIN DC V No. MNEMONIC EQUIVALENT CIRCUIT PIN PIN DC V No. MNEMONIC EQUIVALENT CIRCUIT
10 LIMITER OUT 11 +1.25
11 8.8k
IF 16 AMP OUT +1.28
1.31k 16 6.6k
LIMITER 12 DECOUP +1.28 17
IF AMP DECOUP +1.28
14
18 1.5k
LIMITER 13 COUPLING +1.28
IF 18
50A
AMP IN
+1.28
1.5k
50A
12 13 19
17
LIMITER 14 IN +1.28 19
IF AMP DECOUP +1.28
1.87k 20
MIXER 15 GND 0 20 OUT +2.03
October 27, 1993
8
Philips Semiconductors RF Communications Products
Product specification
Low-voltage digital IF receiver
SA637
PAD
48dB PAD
32.2dB PAD
48dB PAD
32.2dB PAD LIMITER OUT (+)
R49 R47 C20 SW9
R29
R32 C29 R31 SW7 C28
R35 R33 C30
R37
R48
R28
R27 C27
R34
C33
R38 FLT1 C26 SW8 FLT2 SW6 C31 C32
20
19
18
17
16
15
14
13
12
11
IF AMP MIXER
LIMITER
FAST RSSI OSCILLATOR RSSI BUFFER +- LO BUFF +- RSSI FB
1
C1
2
3
4
5
C22
6
7
R16
8
9
10
R50
C2 C4 L2 R2
C6 C5 R17 C11 R20 C21
C3
R14 R13 R1 RF IN R3 LIMITER OUT (-) R4 R45 C12 R51
LO IN
OSC OUT
VCC
RSSI
PWD
Automatic Test Circuit Component List C1 C2 C3 C4 C5 C6 C11 C20 C21 C26 10nF 91pF 620pF 100nF 100nF 10nF 100nF 100nF 100nF 100nF C27 C28 C29 C30 C31 C32 C33 R1 R2 R3 100nF 100nF 100nF 100nF 100nF 100nF 100nF 249 60.4 60.4 R4 R13 R14 R16 R17 R20 R27 R28 R29 R31 49.9 10k 10k 10k 1k 10k 13.7k 1.68k 49.9 1k R32 R33 R34 R35 R38 R39 R45 R47 R48 R49 49.9 13.7k 1.68k 49.9 1k 49.9 49.9 2.43k 39.2k 49.9 R32 R50 R51 L2 49.9 1k 49.9 62nH
Figure 1. SA637 Automatic Test Circuit October 27, 1993 9
Philips Semiconductors RF Communications Products
Product specification
Low-voltage digital IF receiver
SA637
FLT1 C3 C4 FLT2 C5 C6 C11
20
19
18
17
16
15
14
13
12
11
IF AMP MIXER
LIMITER
RSSI RSSI BUFF OSCILLATOR L4 +- RSSI FB LO + - BUFF
*
R5
1
L1 C1
2
3
4
5
C8
6
C9
7
R2
8
9
10
C13
*
L3 RF INPUT C12 C2 C14 C7 R1
*
X1 R3
R9
* R4
L5
*
R6
*
*
C10 R8 R7
C15 L2
*
*
OSC OUT VCC RSSI POWER LIMITER DOWN OUT(-) LIMITER OUT(+)
Component List
C1 C2 C3 C4 C5 C6 C7 C8
5-30pF 5-30pF 0.1F 0.1F 0.1F 0.1F 10pF 0.1F
C9 C10 C11 C12 C13 C14 C15
0.1F 1.0F 0.1F 68pF 0.1F 0.1F 1000pF
R1 R2 R3 R4 R5 R6 R7 R8 R9
OPEN 0 (short) 1k 1.0k 2.0k 51 100 100 OPEN
L1 L2 L3 L4 L5 FLT1 FLT2 X1
0.15H PM20-R15M 0.15H PM20-R15M 0.47H PM20-R47M OPEN OPEN 455kHz SFGCC 455BX-TC 455kHz SFGCC 455BX-TC 82.705MHz CTS XTAL 020-3249-042
* NOTE: These components are optional and depend on user matching requirements. Pads are provided on the demo board. R2 and R9 set the RSSI buffer gain. For unity gain short R2 (Pin 7 to Pin 8) and leave R9 open.
Figure 2. SA637 Application Circuit 10
October 27, 1993
Philips Semiconductors RF Communications Products
Product specification
Low-voltage digital IF receiver
SA637
RF GENERATOR 83.16MHz
SA637 DEMO BOARD RSSI LIMITER OUTPUT VCC = 3V
SPECTRUM ANALYZER DC VOLTMETER
Figure 3. SA637 Application Circuit Test Set Up NOTES: 1. Carrier-to-Noise (C/N): Connect a spectrum analyzer to Pin 10 or 11; set your RF generator to 83.16MHz or 455kHz above your LO frequency, modulation off; set the spectrum analyzer resolution bandwidth to 300Hz; and adjust your RF input level until the C/N = 26dB. Use video averaging. Assure that LIMOUT(+) and LIMOUT(-) are matched symetrically. 2. Ceramic filters: The ceramic filter can be SFGCC455BX-TC made by Murata which has 30kHz IF bandwidth. 3. Sensitivity: The measured typical sensitivity for 12dB SINAD should be 0.45V or -114dBm at the RF input. 4. Layout: The layout is very critical in the performance of the receiver. We highly recommend our demo board layout. 5. RSSI: The smallest RSSI voltage (i.e., when no RF input is present and the input is terminated) is a measure of the quality of the layout and design. If the lowest RSSI voltage is 500mV or higher, it means the receiver is in regenerative mode. In that case, the receiver sensitivity will be worse than expected. 6. Supply bypass and shielding: All of the inductors, the quad tank, and their shield must be grounded. A 0.1F bypass capacitor on the supply pin improves sensitivity.
October 27, 1993
11
Philips Semiconductors RF Communications Products
Product specification
Low-voltage digital IF receiver
SA637
October 27, 1993
12

▲Up To Search▲

Price & Availability of SA637DK

	To Download SA637DK Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .