Parabolic correction signal amplitude control loop.

摘要

A deflection waveform correction signal generator comprises a multiplying circuit (U2) for generating a pincushion correction signal (ICOR). A horizontal frequency ramp (R) is generated by a clipped retrace pulse (HZC). The ramp generator (Q2, C2) has a output (R) coupled to an integrating circuit (U1) for generating a parabolic shaped signal (P). The ramp generator (Q2, C2) and ramp integrator (U1) are reset at a horizontal rate by reset pulses of differing duration. The different duration of reset pulses results in the parabolic signal (P) having regions of non-parabolic shape. The parabolic shaped signal (P) is coupled to an input of the multiplying circuit (U2). A control circuit (300) is coupled to the parabolic shaped signal (P) for maintaining a peak amplitude thereof by controllable coupling to the ramp generator (Q2, C2). A control loop (400) is coupled to the integrator (U1) for controlling an integrator input bias current (IT) to generate the parabolic shaped signal (P) at a predetermined time interval.