Masao Kawashima

400 Mbit/s Digital Repeater Circuitry Provided by a New Design Method and Beam Lead GHz Transistors

A stable, compact, and high-performance regenerative repeater circuitry, suitable for digital transmission systems up to several hundred Mbit/s, has been provided through utilization of new devices, such as 7 GHz beam lead shielded junction transistors, and through a new computer-aided design method, and has been successfully applied to the 400 Mbit/s experimental coaxial cable PCM system. Major features of this repeater circuitry are: (1) an equalizing amplifier with low noise figure (7.6 dB), small intersymbol interference (12%), and automatic line equalization of 21 dB tracking range at 200 MHz; (2) a regenerative output circuit with bipolar pulses of 2.4 Vop amplitude and 700 ps rise time; and (3) total performance with sufficient noise margin (10 dB for error rate 10-11over a line of 56 dB loss at 200 MHz), small static pattern jitter (20°pp), smaller size ( 270 \times 160 \times 52 mm), and lower power (5.8 W). These have been achieved by use of: (1) new devices such as beam lead transistors with f T of 7 GHz, Le of 0.2 nH and Cob of 0.4 pF and tantalum thin film hybrid integrated circuits; and (2) a new CAD system including block simulation, network design/ simulation, layout design subsystems which use transmission quality (error rate and jitter) as a design criterion, and which can also be directly connected to the manufacture automation systems, e.g., for mask preparation, and transistor mounting by bonding.

APC Systems Used in Broadband Carrier Systems for Video Signal Transmission

From the viewpoint of better utilization of synchronization information in suppressed carrier VSB (vestigial sideband) television signals, various carrier regeneration and phase tracking systems are examined. Two APC (automatic phase control) systems with improved utilization of synchronous information are discussed further with emphasis placed on their precision phase tracking and carrier regeneration characteristics. Test models of both systems have obtained a carrier phase accuracy of ± 0.5 degree, which permits color television transmission over a chain of long haul links. Practical utilization of the first system, which employs an approximateBSB(both sidebands) component is featured by the use of a variable parameter phase tracking control loop system which attains a stable, high sensitivity. To satisfy stability, sensitivity, and practical requirements, a second-order variable parameter astatic zero tracking system has been adopted. Response of the test equipment to a typical picture has been analyzed, and the theoretical results have been verified by experiment. If the sensitivity parameter is fixed, the first system becomes the phase tracking circuitry of the second system. This is a carrier reproducing system which uses time band filtering, sampling, and which must fully utilize trisynchronization (V- and H-synch and blanking) information to secure the start and continuance of sampling. Its carrier regeneration system features the use of a self-holding gate which synchronously gates by using the natural and horizontal synchronous periods and not regating for a certain fixed time period. The stationary and starting transient responses of this system are discussed and its reliable starting verified through experimentation. It has been found to be effective with an ECR (excess carrier ratio) of 0.5. A phase tracking method similar to that in the first system was used.