A 2-20 GHz SiGe Amplitude Control Circuit with Differential Signal Selectivity for Wideband Reconfigurable Electronics

Abstract

This paper presents a wideband integrated single-tap circuit for a general-purpose, high-performance transversal filter application, and which has been implemented in silicon germanium (SiGe) technology for use in direct-throughput processing of RF signals in the microwave and millimeter-wave spectrum. To provide wideband instantaneous reconfigurability and multi-function RF capability, the proposed circuit consists of a digital step attenuator, an active-based balun, a single-pole single-throw (SPDT) switch, and a digital control circuit. To achieve low noise characteristics for the receiver, a wideband low-noise amplifier (LNA) is included in the design. In addition, an active-based switchable power divider is utilized for supporting open-loop systems that provide a comparison with system set points or input signals. The proposed single-tap circuit demonstrates flat in-band gain of 14.3 dB with ±0.9 dB variation, 31.5 dB amplitude control range with 0.5 dB step, and a differential signal selectivity from 2 to 20 GHz. This single-tap circuit block is expected to enable a diverse set of tasks, including tunable RF front-end filtering, pre-linearization of signal for saturation compensation, and direct throughput matched filtering.