AD539:  Wideband Dual-Channel Linear Multiplier/Divider

The AD539 is a low distortion analog multiplier having two identical signal channels (Y1 and Y2), with a common X input providing linear control of gain. Excellent ac characteristics up to video frequencies and a −3 dB bandwidth of over 60 MHz are provided. Although intended primarily for applications where speed is important, the circuit exhibits good static accuracy in computational applications. Scaling is accurately determined by a band-gap voltage reference and all critical parameters are laser-trimmed during manufacture.

The full bandwidth can be realized over most of the gain range using the AD539 with simple resistive loads of up to 100 Ω. Output voltage is restricted to a few hundred millivolts under these conditions.

The two channels provide flexibility. In single-channel applications, they can be used in parallel to double the output current, in series to achieve a square-law gain function with a control range of over 100 dB, or differentially to reduce distortion. Alternatively, they can be used independently, as in audio stereo applications, with low crosstalk between channels. Voltage-controlled filters and oscillators using the state-variable approach are easily designed, taking advantage of the dual channels and common control. The AD539 can also be configured as a divider with signal bandwidths up to 15 MHz.

Power consumption is only 135 mW using the recommended ±5 V supplies. The AD539 is available in three versions: the J and K grades are specified for 0 to 70°C operation and S grade is guaranteed over the extended range of −55°C to +125°C. The J and K grades are available in either a hermetic ceramic SBDIP (D-16) or a low cost PDIP (N-16), whereas the S grade is available in ceramic SBDIP (D-16) or LCC (E-20-1). The S grade is availa¬ble in MIL-STD-883 and Standard Military Drawing (DESC) Number 5962-8980901EA versions.

APPLICATIONS

• Precise high bandwidth AGC and VCA systems
• Voltage-controlled filters
• Video signal processing
• High speed analog division
• Automatic signal-leveling
• Square-law gain/loss control