Optimization of synthesis filters for hybrid filter bank DACs

Hybrid filter bank (HFB) is a promising technology that both improve the resolution and speed of digital-to-analog conversion. In this letter, we present a wideband waveform generation method using HFB architecture. Mixers are adopted to break through the limitation caused by zero-order-hold (ZOH) of DACs. However, the imperfect match of analysis filters and synthesis filters significantly degrade the system performance. To solve this problem, we analyze the influence of filter mismatch. An analysis filter design based on weighted least squares (WLS) and an optimization design for synthesis filter is presented. The optimization method invokes the WLS method at each iteration. Performance evaluation shows that these two methods work together and perform a better reconstruction system than the WLS method which just focus on analysis filter bank.