Design of novel high isolation RF wideband low noise amplifier for digital TV applications

In this paper the design of a high gain low noise amplifier is presented. The LNA was successfully designed to operate over VHF and UHF ranges according to DVB-T specifications. The novelty of the design lies in the achievement of low noise figure across a wide bandwidth and high reverse isolation level. The latter was required in order to integrate the front-end block to a direct-conversion receiver. Such isolation would not normally be achieved with the resistive feedback technique employed here to enhance the operating bandwidth. A measured compression point of P_1dB=-10 dBm, a small-signal gain = 16 dB and gain flatness of less than 1 dB ripple, have all met commercial specifications tested over corners. Noise figure achieved was better than specified and was less than 2 dB over all the bandwidth. The paper shows design and measurements techniques that enabled the successful implementation of this front-end block using a commercial 0.25u Si BiCMOS process.