Power-amplifier inserted transversal filter using high-order pass band

Power amplifier inserted transversal filter amplifies in high efficiency and can adjust the center frequency and pass bandwidth. In addition, the filter suppresses the quantization noise that remains outside the desired signal band at the output of the filter. The reduction of the quantization noise is due to narrowing the pass bandwidth by increasing the number of paths. However, the circuit scale and the loss in power combining in the filter increase as the number of paths increases. To solve this problem, this paper proposes to use the higher-order passband of the transversal filter to narrowing the filter by increasing the delay difference between adjacent paths of the filter. This realizes passband characteristics almost equivalent to a large number of paths. In addition, this enables to suppress the increase in circuit scale and losses due the power combining. Computer simulation shows that a narrow-band filter can be realized with a small number of paths by using a higher-order passband. It also shows that the degradation in modulation accuracy is small due to the use of higher-order passband.