Abstract:
An output driver. The novel output driver includes a first circuit for receiving an input signal and in accordance therewith generating an output signal at an output node, a second circuit for applying a variable current to the output node, and a third circuit for controlling the magnitude of the variable current in accordance with the input signal. In an illustrative embodiment, the third circuit is adapted to generate a controlling current in accordance with the input signal, and the second circuit includes a current mirror adapted to receive the controlling current and output a scaled version of the controlling current to the output node.
Abstract:
A sample and hold circuit including a first arrangement for receiving an input signal; a second arrangement for sampling and holding the signal in response to a control signal; and a third arrangement for minimizing the change in an input transistor's base current when the circuit switches from track to hold or hold to track and for keeping the collector emitter voltage constant at the input transistor. An arrangement is disclosed to increase the dynamic current accuracy of a current mirror for a diode connected transistor, by holding the voltage across one transistor in the current mirror constant. Another arrangement is disclosed for holding collector to emitter voltage constant for intermediate transistors resulting in improved gain accuracy and linearity. In one embodiment, a dummy leg is added to isolate the output voltage from switching transients that occur when an intermediate transistor is turned on at the transition from track to hold.
Abstract:
An active load circuit for automatic test equipment that tests integrated circuits. The active load circuit includes a current source; a current sink; a current switching switching circuit having current source and current sink nodes respectively connected to the current source and the current sink; and a control circuit for controlling the current switching circuit with a differential voltage that is limited in amplitude and of the same polarity as a voltage difference between a fixed reference voltage and a pin output voltage of a device under test.
Abstract:
A method of integrating MEMS devices with non-MEMS circuitry requires fabricating non-MEMS devices on a substrate in a conventional fashion. A thick dielectric layer is deposited on the completed devices, and the MEMS devices fabricated on the dielectric layer. Vias through the dielectric layer interconnect the MEMS devices to the non-MEMS electronics. The interposed dielectric layer allows the common substrate to have characteristics that best suit the non-MEMS components, without degrading the MEMS performance. Another approach involves bonding together two separate wafers—one for the MEMS devices and one for non-MEMS electronics. A package lid, having filled vias formed therethrough, is bonded to the MEMS wafer, sealing the MEMS devices within. The non-MEMS wafer is mounted to the lid, with the vias effecting the necessary interconnections between the two wafers. This enables the MEMS devices and the non-MEMS electronics to function as a single IC, while retaining the established processes associated with each component type.
Abstract:
A unit cell including a substrate; an active circuit disposed on the substrate; and an arrangement disposed on the substrate for routing a plurality of conductors thereover. In the illustrative implementation, the routing arrangement includes first, second and third ground planes disposed on the substrate, a first layer of conductors disposed between the first and second planes, and a second layer of conductors disposed between the second and the third planes. Each cell is adapted to connect to a device such as a detector. The inventive unit cell enables an improved focal plane array design with a smaller unit cell supporting smaller detector sizes. Smaller detector pitch allows higher density detector arrays. The inventive fan-out approach allows for complicated circuitry to be located outside the array. This permits the utilization of more sophisticated analog signed processing, such as a multiple sample approach. Multiple sampling results in a much more accurate digital Gaussian curvefit, which increases the range and intensity accuracy of readout electronics.
Abstract:
An apparatus for selectably converting emitter-coupled logic (ECL) and positive emitter-coupled logic (PECL) signals to negative complimentary metal oxide semiconductor (NCMOS) signals is disclosed. The apparatus uses an input level shifter, a secondary level shifter, and an output buffer to convert the ECL and PECL differential signals to single-ended signals. The apparatus also includes a disable output function for disabling the output of the output buffer. The apparatus may be integrated multiple times on a substrate containing NCMOS circuitry, thereby allowing the NCMOS circuitry to be driven by differential signals. Alternatively, the present invention may be integrated multiple times onto a single substrate to create a dedicated universal translator.
Abstract:
An improved high speed PIN driver integrated circuit and architecture. The architecture of the PIN driver circuit does not rely on transistor clamping during normal operation in active mode, and does not require high reverse base-emitter breakdown voltage in inhibit mode or the active mode, which is in direct opposition to high speed performance at high PIN voltage excursions for CMOS, TTL, ECL level compatibility. In particular, the PIN driver circuit is always an active linear circuit and does always protects the reverse base-emitter voltage of any transistor and does not require wire-OR or clamp transistors. The architecture uses replica biasing to cancel the current of the PIN driver in the inhibit mode, which is a requirement for automatic test equipment where the leakage current produces at the PIN in the inhibit mode is not calibrated out. The replica biasing is implemented using a current mirror circuit, a summing device and a buffer circuit which generates the voltage replica in an active mode of the PIN driver circuit. The replica biasing scheme used in the present invention tracks over temperature and process, and provides for improved high speed circuitry without the need for calibration of leakage currents in the inhibit mode.
Abstract:
A current steering circuit diverts bias current from a differential current summing amplifier's front end when the differential input exceeds a safe threshold level, thus preventing the amplifier's output stage from being overdriven. Diverting the front end's bias currents also turns off transistors within the amplifier's front end and thus protects the front end from damage which may otherwise result from excessive input signals.
Abstract:
A non-attenuating automatic variable gain amplifier (VGA) circuit includes an operational amplifier (op amp) with a feedback resistor connected between its output and inverting input terminals. A variable gain setting resistance circuit having a variable resistance is the gain setting resistor positioned between the op amp's inverting input and a low voltage supply. By varying the resistance of the variable resistance circuit, the gain of the VGA circuit can be manipulated without requiring attenuation of the input signal. A resistance setting control for the variable resistance circuit can operate open loop, fed back from the amplifier output, or fed forward from the amplifier input.
Abstract:
First and second current feedback transconductance amplifiers (102,104) each have a high impedance voltage input, a low impedance current input and a pair of push-pull current outputs. In a single-ended configuration, an input signal is applied to the voltage input of the first transconductance amplifier (102) and the push-pull outputs of the both transconductance amplifiers are connected through a current mirror (136,138) to a node (134) where the current outputs are summed. The node current is integrated by a capacitor (174) to produce a voltage which is amplified by a transimpedance amplifier (190) to produce an output voltage which is fed back to the voltage input of the second transconductance amplifier (104). The current inputs of the transconductance amplifiers (102,104) are interconnected by a resistor (132). The high impedance voltage inputs produce common-mode cancellation of distortion in the transconductance amplifiers (102,104) and low input shot noise. In a differential configuration, differential input signals are applied to the voltage inputs of transconductance amplifiers (260,262), and a separate transimpedance amplifier (292,316) and current mirror (278,280) (302,304) is provided for each transconductance amplifier (260,262). A common-mode feedback circuit (352) controls the common-mode output voltages of the transimpedance amplifiers (292,316) to ground. Switch means (402,404,406,408,410,412) may be added to selectively ground the voltage inputs of the transconductance amplifiers (260,262) and disable their input stages by disconnecting their power supplies (VCC,VEE).