500 MHz Four-Quadrant Multiplier
The AD834 is a monolithic, laser-trimmed four-quadrant analog multiplier intended for use in high frequency applications, with a transconductance bandwidth (RL = 50 Ω) in excess of 500 MHz from either of the differential voltage inputs. In multiplier modes, the typical total full-scale error is 0.5%, dependent on the application mode and the external circuitry. Performance is relatively insensitive to temperature and supply variations due to the use of stable biasing based on a band gap reference generator and other design features.
To preserve the full bandwidth potential of the high speed bipolar process used to fabricate the AD834, the outputs appear as a differential pair of currents at open collectors. To provide a single-ended ground referenced voltage output, some form of external current-to-voltage conversion is needed. This may take the form of a wideband transformer, balun, or active circuitry such as an op amp. In some applications (such as power measurement), the subsequent signal processing may not need to have high bandwidth.
The transfer function is accurately trimmed such that when X = Y = ±1 V, the differential output is ±4 mA. This absolute calibration allows the outputs of two or more AD834 devices to be summed with precisely equal weighting, independent of the accuracy of the load circuit.
The AD834J, available in 8-lead PDIP and plastic SOIC packages, is specified over the commercial temperature range of 0°C to 70°C. The AD834A is also available in 8-lead CERDIP and plastic SOIC packages operating over the industrial temperature range of−40°C to +85°C. The AD834SQ/883B, available in an 8-lead CERDIP, operates over the military temperature range of −55°C to +125°C. S-grade chips are also available.
Two application notes featuring the AD834 (AN-212 and AN-216) can be found at www.analog.com. For additional applications circuits, consult the AD811 data sheet.