Ultra-low Noise Preamplifier

The CLC5509 is a high performance, ultra-low noise pream- plifier designed for applications requiring unconditional sta- bility for wide ranges of complex input loads. Both input im- pedance and gain are externally adjustable, which make it simple to Interface to peizoelectric ultrasound transducers. The CLC5509 preamplifiers low 0.58nV total input noise makes it ideal for noise sensitive front ends. The high repeatability in group delay over voltage and temperature translates into precision edge measurements for Doppler ap- plications. The IC consists of an emitter input, common base Amplifier stage followed by a low distortion, closed loop Buffer Exter- nal negative feedback creates a well controlled input imped- ance to allow a near noiseless active input transmission line termination. The preamp is stable against changes in source impedance of 50 to 200 over temperature and supply variations, with gains from 14dB to 26dB. The CLC5509 preamp architecture is also well suited for use with magneto-resistive tape or disk drive heads. In these applica- tions the head bias current CAN be reused to bias the preamp. The part is packaged in an 8-pin plastic SOIC, and runs off 5V supplies. External biasing is required for the in- put signal path. The CLC5509 is constructed using an advanced comple- mentary bipolar process and National Semiconductors proven high performance architectures. By National Semiconductor Corporation