Abstract: An optical analog-to-digital converter (10) which fully operates in the optical domain and utilizes an upward-folding successive approximation approach for conversion. The converter (10) includes a plurality of optical stages (14, 16, 18) where each stage (14, 16, 18) generates a digital bit. Each stage (14, 16, 18) includes an optical threshold switch (30, 56, 78) that sets the bit high when the switch (30, 56, 78) is closed. When a sample amplitude of the analog signal is compared to a threshold value and found to exceed the threshold value, the bit is set to "high" and the sample is passed directly onto the next stage (14, 16, 18). If the sample amplitude is found to be less than the threshold value, the bit is set to "low" and an intensity equal to the maximum signal intensity minus the threshold intensity is added to the sample amplitude. Each successive stage (14, 16, 18) compares the normalized signal sample to thresholds growing closer and closer to the maximum signal intensity.

Abstract: A wireless MMIC chip packaging scheme where the MMIC chip (38) is maintained right side up. The MMIC chip (38) is positioned within a cavity (40) of a fixture (42), where a backside metal layer (44) of the chip (38) is mounted to the fixture (42) by a conductive epoxy layer (48). RF and DC via feedthroughs (62, 64) are strategically provided through the chip (38), and are electrically connected to isolated islands (70) in the backside metal layer (44). Substrates (52, 56) are provided that carry microstrips (54) and electrical traces (56), and that extend below the chip (38) so that ends of the microstrips (54) and traces (56) make an electrical connection with the isolated islands (70). In an alternate design, the substrate (80) extends completely across the backside of the chip (38), and ground vias (84) extend through the substrate (80) to connect the backside metal layer (44) to the fixture (42).

Abstract: A frequency modulation-based optical analog-to-digital converter utilizes a downward-folding, successive approximation approach. A series of stages is utilized to generate bits in the digital signal. In each stage, complementary low and high bandpass filters collectively cover a bandpass frequency range from a low frequency to a high frequency. The high frequency filtered signal from the high bandpass filter is observed to obtain a bit in the digital word. By performing the folding operations in the frequency domain, the converter avoids the difficult task of optical power subtraction, relying instead on frequency down-conversions. The high frequency filtered signal passed by the high bandpass filter is then downconverted and added to the low pass filter signal to generate a modulated signal for the next stage.

Abstract: A distributed amplifier topology with distributed feedback includes a plurality of amplifier stages, each of which includes a FET, MESFET or HEMT. A negative feedback network is provided with each amplifier stage which enables the gain of the distributed amplifier to be reduced by varying the negative feedback. An important aspect of the invention relates to the fact that the gain can be varied with virtually no affect on the bandwidth performance of the product and without significantly affecting the return loss, IP3 and noise figure performance of the device.

Abstract: A method for multi-mode autonomous selection demodulation is disclosed. The method includes the step of providing a receiver with demodulation circuitry (110-112) capable of demodulating a plurality of waveform modulation techniques. The method also includes the step of receiving a modulated information waveform and a preamble associated with the modulated information waveform. The method also includes the steps of matching the preamble against a predefined set of patterns corresponding to a plurality of modulation techniques at the receiver and identifying a corresponding demodulation technique. Additionally, the method configures the demodulation circuitry (110-112) to apply the corresponding demodulation technique to the modulated information waveform.

Abstract: An optical inverter (10) that uses a saturable absorber (28) to distinguish between a logical one and a logical zero. A low power laser (18) generates an optical beam that is split into a first beam that propagates among a first beam path (24) and a second beam that propagates along a second beam path (26). The saturable absorber (28) is an optical switch that is positioned in the first beam path (24), and is switched from an opaque mode to a transparent mode when it receives an optical input signal. The first beam and the second beam are recombined as an optical output beam in an optical combiner (30). The first beam path (24) and the second beam path (26) have a length relative to each other such that the first and second beams are 180.degree. out of phase when they reach the optical combiner (30). Therefore, if the saturable absorber (28) is switched to the transparent mode, the first and second beams combine destructively and the optical output beam is dark, or a logical zero.

Abstract: A switched resonator formed from a series capacitor and a single microstrip transmission line with a plurality of RF switches to connect it to ground along its length. The microstrip transmission line is grounded at one end and the RF switches are used to tune its length. The other end of the microstrip transmission line is connected to the capacitor to form a resonator. The resonant frequency of the resonator is varied by grounding the center conductor through RF switches connected to ground at different points along its length, which effectively varies the electrical length of the transmission line connected to the capacitor thereby forming a switched resonator. The switched resonator is suitable for use with a single VCO to provide relatively wideband tuning of the significantly reduced size due to the use of a single VCO.

Abstract: A reflection reducing directional coupler provides an output signal from a coupled signal while reducing the effect of an input signal. The directional coupler provides circuitry to divide, phase delay and vectorially add signals to provide coherent output and coupled signals and reduce reflected signals. The directional coupler also provides the capability to input a calibration signal into a system while mininimizing the effect of the calibration signal on the output signal.

Abstract: A photonic interconnect and photonic processing apparatus (10) for use in a communication and data handling satellite (12) is disclosed. The photonic interconnect and photonic processing apparatus (10) includes a receiving device (14) for receiving a plurality of input RF signals. An optical conversion device (28) coupled to the receiving device (14) converts the plurality of input RF signals to a plurality of input optical signals. This plurality of input optical signals are coupled to a plurality of input optical fibers (30). A distribution device (32) optically coupled to the optical conversion device (28) distributes at least one output optical signal from the plurality of input optical signals coupled to the plurality of input optical fibers.