Patent GB-1516744-A (GB)
Title: Charge transfer device
IPC: G11C19/36
Filed: 1975-11-14
Abstract: 1516744 Charge transfer device RCA CORPORATION 14 Nov 1975 [18 Nov 1974] 47076/75 Heading G4A A charge transfer memory includes a storage matrix 12 (Fig. 1) having M columns and rows 34 . . . 42, and an N phase output register 18<SP>1</SP> having N electrodes, each controlled by a different one of N phase signals, L of the electrodes of a stage being aligned with columns of the matrix so that the groups of M/L charge signals are fed at a time to the output register 18<SP>1</SP>, M/L signals being read from the register 18<SP>1</SP> before the next group of charge signals is read into it. As described N = L = 2 and M=12, the register having 6 stages. An input register 10 also has 6 stages, each 12 bit word being read into the memory rows of the matrix 12, 6 bits at a time, 6 charge packets stored beneath Q A1  electrodes being first transferred to beneath the electrodes of the first row 34 followed by 6 charge packets stored beneath Q A2  electrodes. To transfer the contents of row 34 to row 36, Q A4  is made more positive and Q B3  is made negative. This process is then repeated for the second word. The last row 42 comprises an electrode pair 42a, 42b (Fig. 2), electrode 42a (made of polysilicon or aluminium) acting as a transfer electrode and electrode 42b (made of aluminium) acting as a storage electrode. Fingers on the electrode 42b interleave with fingers on the electrode 16-3 of output gate 16, which has four electrodes 16-1, 16-2, 16-3, 16-4. The output register 18 is formed of electrode pairs 50a, 50b; 52a, 52b . . . In alternate channels of the matrix, e.g. channel 53 in which finger 42b-2 underlies electrode 16-2 charge propagates via the potential wells beneath electrodes 16-2, 16-3, 16-4 from beneath the electrode 42b to beneath electrode 52b when signals G-2B, G-2C and then signal G-2D are negative to that successive Q C1 , Q C2  signals propagate the half word out of the register via stage 20 to switching circuit 22 for recirculating via lead 28 or output via lead 26 or both. In the other channels, e.g. channel 51, subsequently signals G-2A, G-2B, G-2C go negative followed by signal G-2D to cause the transfer of charge to beneath electrode 52B. In a modification of output gating (Fig. 6), the four electrodes are rectangular and the whole word is propagated beneath electrode 60-2 to beneath electrode 60-4. The charge present in alternate electrodes (Q C1  electrodes) then passes beneath electrode 66a to beneath electrode 66b of the output register, subsequently the half word remaining beneath electrode 60-4 is returned to beneath electrode 60-2. The half word present in the output register is then fed out before the remaining half word is propagated to beneath electrode 60-4. In a further modification (Fig. 8, not shown) three-phase signals are used with one of the electrodes (82-3) of the output gate isolating the third of the word propagating in the output register from the remainder of the word held beneath G-2B electrodes. In a further modification (Figs. 11, 12, not shown) two channels of the matrix are associated with each threephase stage.