An analog sampled-data DSB to SSB converter using recursive Hilbert transformer for accurate I and Q channel matching

The realization of a complete double-sideband (DSB) to single-sideband (SSB) converter using switched-capacitor techniques is presented. The proposed approach employs a recursive Hilbert transformer to achieve efficient SSB modulation. The design of the Hilbert transformer through structurally all-pass networks allows good dynamic range and small sensitivity to capacitance ratio errors. The sampling rate of the output SSB signal is reduced by a factor of two, so that the Hilbert transformer and the following circuitry work at half of the input sampling rate, reducing circuit complexity and power consumption, without loss of information. Experimental laboratory results obtained with a prototype realization using discrete components are presented. Practical aspects pertaining to a monolithic implementation in complementary metal-oxide-semiconductor (CMOS) technology are considered.