Abstract

A first-order Delta-Sigma ( ∆Σ ) modulator has been fabricated using a 70GHz (fT) AlInAs/GaInAs-InP HBT technology. At a sampling rate of 2GHz, it converts a 50MHz signal with a maximum signal-to-noise ratio (SNRmax) of 19dB and a dynamic range (DR) of 25dB, equivalent to 3.9DRbits. With a 10MHz signal, 36.5dB DR (5.8DRbits) and 30.8dB SNRmax are achieved. The modulator has been designed in a fully differential architecture, and dissipates 330mW from a -5V power supply. This paper presents the performance of a first-order, continuous-time, low-pass ∆Σ modulator. To date only a few results have been reported for first-order ∆Σ modulator implemented in a III-V technology. A first-order architecture represents a fundamental first step in the design of higher order modulator offering better performance.