An Integrated IF Amplifier and Detector for an A.M. Upconversion Radio
This paper presents a monolithically integrated IF amplifier and envelope detector for an AM upconversion car-radio receiver. This receiver is intended for the reception of the long-wave and medium-wave frequency bands and uses an intermediate frequency of 10.7 MHz. Specific requirements resulting from the upconversion concept will be illustrated and the basic considerations for maximization of the signal-to-noise ratio as a function of the input signal level will be given. Furthermore, a new method will be presented for fixing the signal levels and the AGC speed in the amplifier. The amplifier uses two emitter-driven variable-gain pairs alternated by negative-feedback current amplifiers. It has an AGC range of 90 dB and a gain of 66 dB. The audio output level is constant within 0.2 dB over the full controll range. A cross-quad compensated envelope detector is driven at a level as low as 30 mV and shows less than 3-percent distortion at a modulation depth of 80 percent.
A High-Dynamic-Range Front End for an Upconversion Car-Radio Receiver
A monolithically integrated high-performance front end for an AM radio receiver is presented. Medium- and long-wave reception without any tuned-circuit alignments or band switches is made possible by using an intermediate frequency of 10.7 MHz, well above the maximum frequency to be received. Image- and oscillator-harmonics-related spurious responses are rejected by a simple low-pass filter. The upconversion concept puts high demands on the front-end circuits. A high intermodulation free dynamic range is realized by applying several unconventional and new circuit techniques. A low-noise low-distortion wide-band input amplifier with capacitive negative feedback realizes the required antenna match. The gain of this amplifier is automatically switched to a lower value in the vicinity of transmitters with high field strengths. A double-balanced mixer, driven by an oscillator employing a novel amplitude stabilization technique, provides the frequency conversion up to 10.7 MHz. Digital toning can be achieved very simply because only the local-oscillator frequency has to be varied. The dynamic range of this front end amounts to 130 dB. Field strengths up to about 20 and 200 mV/m can be handled without noticeable second- and third-order intermodulation, respectively.
PULSE: a high-repetition-rate linac driver for x-ray FELs
We describe a staged concept for a linac-based freeelectron laser providing coherent tuneable VUV and soft X-ray output with pulse lengths down to 10 fs or less. Use of 1.3 GHz cryomodules operated with CW RF will allow flexible pulse patterns at potentially very high repetition rates up to 1 MHz. We consider the options for FELs that may be included in a facility of this type.