SL6440

SL6440 ZARLINK | Alldatasheet

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The SL6440 is a double balanced mixer intended for use in radio systems up to 150MHz. A special feature of the circuit allows external selection of the DC operating conditions by means of a resistor connected between pin 11 (bias) and Vcc When biased for a supply current of 50mA the SL6440 offers a 3rd order intermodulation intercept point of typically +30dBm, a value previously unobtainable with integrated circuits. This makes the device suitable for many applications where diode ring mixers had previously been used and offers the advantages of a voltage gain, low local oscillator drive requirement and superior isolation.

FEATURES

■ +30dBm Input Intercept Point ■ +15dBm Compression Point (1dB) ■ Programmable Performance ■ Full Military Temperature Range (SL644A)

APPLICATIONS

■ Mixers in Radio Transceivers ■ Phase Comparators ■ Modulators

ORDERING INFORMATION

Fig.1 Pin connections - top view DG16 DP16 Min. Typ. Max. Signal frequency 3dB point 100 150 MHz Oscillator frequency 3dB point 100 150 MHz 3rd order input intercept point +30 dBm Third order intermodulation distortion -60 dB Two 0dBm input Second order intermodulation distortion -75 dB Signals 1dB compression point 15 dBm V CC 1 = 15V VCC 2 = 12V VCC 1 = 12V VCC 2 = 10V Noise figure 11 dB Fig.8 test circuit Conversion gain -1 dB 50 Ω load Fig.2 Carrier leak to signal input -40 dB Test circuit Fig.8 Level of carrier at IF output -25 dBm See applications information Supply current 7 mA I P = 0 Supply current (total from VCC 1 & VCC 2) 60 mA Local oscillator input 100 250 500 mV rms I P = 35mA Local oscillator input impedance 1.5 k Ω Signal input impedance 500 Ω Single ended 1000 Ω Differential Characteristic Units Conditions Value NOTE Supply current in Pin 3 is equal to that in Pin 14 and is equal to IP See over. Vpin11 3Vbe 2.1V.

ELECTRICAL CHARACTERISTICS

Test condltions (unless otherwise stated): VCC 1 = 12V; VCC 2 = 10V; IP = 25mA; Tamb = -55°C to +125°C (SL64440A), -30°C to +85°C (SL6440C) Local oscillator input level = 0dBm; Test circuit Fig.2. ABSOLUTE MAXIMUM RATINGS Supply voltage and output pins 15V Maximum power dissipation 1200mW (Derate above 25°C: 8mW/°C) Storage temperature range -65 °C to +150°C Programming current into pin 11 50mA THERMAL CHARACTERISTICS Thermal resistance: 0JA 125°C/W 0JC Time constant: Junction-Ambient 1.9 mins Maximum chip temperature 150 °C

The SL6440 is a high level mixer designed to have a linear RF performance. The linearity can be programmed using the IP pin (11). The output pins are open collector outputs so that the conversion gain and output loads can be chosen for the specific application. Since the outputs are open collectors they should be returned to a supply V CC 1 through a load. The choice of VCC 1 is important since it must be ensured that the voltage on pins 3 and 14 is not low enough to saturate the output transistors and so limit the signal swing unnecessarily. If the voltage on pins 3 and 14 is always greater than V CC 2 the outputs will not saturate. The output frequency response will reduce as the output transistors near saturation. Minimum V CC 1 = (IP x RL) + VS + VCC2 where IP = programmed current RL = DC load resistance V S = max signal swing at output if the signal swing is not known: minimum V CC 1 = 2 (IP x RL) + VCC 2 In this case the signal will be limiting at the input before the output saturates. The device has a separates supply (VCC 2) for the oscillator buffer (pin 4). The current (IP) programmed into pin 11 can be supplied via a resistor from VCC 1 or form a current source. The conversion gain is equal to GdB = 20 Log for single-ended output GdB = 20 Log for differential output Device dissipation is calculated using the formula mW diss = 2 I P VO + VPIP + VCC 2 Diss where VO = voltage on pin 3 or pin 14 VP = voltage on pin 11 IP = programming current (mA) VCC 2 Diss = dissipation obtained from graph (Fig.6) As an example Fig.7 shows typical dissipations assuming VCC 1 and VO are equal. This may not be the case in pratice and the device dissipation will have to be calculated for any particular application. Fig.5 shows the intermodulation performance against I The curves are independent of VCC 1 and VCC 2 but if VCC 1 becomes too low the output signal swing cannot be accommodated, and if V CC 2 becomes too low the circuit will not provide enough drive to sink the programmed current. Examples are shown of performance at various supply voltages. The current in pin 14 is equal to the current in pin 3 which is equal to the current in pin 11. RL I P 56.61 IP + 0.0785 2RL IP 56.61 IP + 0.0785 Fig.4 Frequency response at constant output IF SL6440 10µ 0.1µ 0.001µ LO INPUT VCC2 OUTPUT 126 0.001µ 0.001µ 11143 0.1µ RF INPUT 10µ0.1µ 500 VCC1 5050 -10 +10 10 20 30 40 50 60 70 (mA) TOTAL OUTPUT CURRENT (2I P) (dBm) VCC 1 = 15V VCC 2 = 12V VCC 1 = 12V VCC 2 = 10V LOCAL OSCILLATOR = 30MHz 0dBm RF INPUT = 40MHz IF = 10MHz -1dBm COMPRESSION POINT Fig.2 Typical application and test circuit Fig.3 Compression point v. total output current -12 -11 -10 10 100 1000 LOCAL OSCILLATOR FREQUENCY MHz 10MHz WANTED OUTPUT RF INPUT 0dBm LOCAL OSCILLATOR INPUT LEVEL V CC 1 = 6V VCC 2 = 5V IP = 24mA VCC 1 = 12V VCC 2 = 10V SIGNAL 10MHz HIGHER THAN LOCAL OSCILLATOR

Fig.5 Intermodulation v. programming current Fig.6 Supply current v. VCC 2 (IP = 0) The SL6440 can be used with differential or singleended inputs and outputs. A balanced input will give bettercarrier leak The high input impedanceallowsstepup transformers to be used if desired, whilst high output impedance allows a choice of output impedance and conversion gain. Fig. 2 shows the simplest application circuit. The input and output are single-ended and Ip is supplied from V CC 1 via a resistor. Increasing RL will increase the conversion gain, care being taken to choose a suitable value for V CC 1. Fig. 8 shows an application with balanced input, for improved carrier leak, and balanced output for increased conversion gain. A lower V CC 1 giving lower device dissipation can be used with this arrangement. DESIGN PROCEDURE 1. Decide on input configuration using local oscillator data. If using transformer on input, decide on ratio from noise considerations. 2. Decide on output configuration and value of conversion gain required. 3. Decide on value of l P and VCC 2 using intermodulation and compression point graphs. 4. Using values of conversion gain, V CC 2, load and Ip already chosen, decide on value of VCC 1. 5. Calculate device dissipation and decide whether heatsink is required from maximum operating temperature conslderatlons. Fig.7 Device dissipation v. IP Fig.8 Typical application circuit for highest performance

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