Abstract: Stray capacitance is reduced in a wideband tunable oscillator network by arranging the resonant circuit as one or more series circuit branches wherein a variable capacitance such as a varactor diode is interposed between two substantially identical inductors. In the disclosed VHF-UHF oscillator, the inductors are realized by TEM transmission lines of the stripline variety. The stripline is formed by a multilayer printed circuit board arrangement and two resonant circuit branches are interconnected in a manner that permits biasing of the varactor diodes without the use of blocking capacitors in the resonant circuit path.

Abstract: A test system for functionally testing and troubleshooting microprocessor-based systems and assemblies is disclosed wherein the test system is connected in place of the microprocessor circuit of the unit being tested (UUT). The test system is itself a microprocessor-based system and includes a microprocessor circuit which is supplied with the UUT clock signal and is the same type of microprocessor circuit as is utilized by the UUT. The test system periodically switches this microprocessor into signal communication with the UUT for a single UUT bus cycle to perform UUT read or write operations. During remaining time periods, the test system microprocessor circuit is in signal communication with the remaining portion of the test system to analyze data obtained from the UUT bus during the previous UUT write or read operation and to establish the signals to be used in the next UUT write or read operation. Various test sequences are provided for testing the UUT bus, RAM, ROM, and write-responsive I/O registers.

Abstract: A precision crystal-controlled oscillator circuit with provision for separate sinusoidal and square-wave output signals which can be realized as a silicon integrated circuit without the use of external capacitors or resistors is disclosed. Two feedback loops are utilized in addition to the oscillating loop. The first feedback loop maintains the gain of the oscillation loop at substantially unity when the amplitude of the oscillation is at a predetermined level, thereby ensuring both spectral purity and amplitude stability of the sinusoidal output signal. The second feedback loop maintains the duty cycle of the square-wave output signal substantially equal to 50 percent by controlling the circuit operation to equally space the signal zero crossings at the input of the square-wave output stage.