標題: 有人care過bandgap可能存在不止1個degenerate points(stable points)嗎？ [打印本頁] 作者: hi.china59 時間: 2009-10-3 12:59 AM 標題: 有人care過bandgap可能存在不止1個degenerate points(stable points)嗎？ 有人care過bandgap可能存在不止1個degenerate points(stable points)嗎？ w. b+ F0 N8 o" v4 y" i; h: i$ u% [. o/ z8 j1 \6 ~) S
The degenerate point of Bandgap reference circuit+ L! b9 s) B; z' {2 N( ]
Q:有人care過bandgap可能存在不止1個degenerate points(stable points)嗎？9 f9 H+ A# z/ g
A: We do care the degenerate points of a bandgap reference circuit. The bandgap reference circuit needs a more effective startup circuit than those usually adopted. The crossing (degenerate) points are much less defined. Please read the attached bandgap degenerate points.pdf : p6 P( |5 ~2 n" {# ~: m
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Low Voltage Bandgap Reference Circuit 7 F& ?& @" Q# ?& fPatent number: 6489835' O4 I; g% z- S* m. Z" r1 K
Filing date: Aug 28, 2001 1 V* U Y1 @' S, e3 f* mIssue date: Dec 3, 2002 5 V- D7 b8 o9 v9 Q* NInventors: Quan Yu, Edwin Chan, _' n; w2 @: a
Assignee: Lattice Semiconductor Corporation 4 N; g8 m* ]+ C. [5 F* b2 y% U; L
Banba et al, in "A CMOS Bandgap Reference Circuit with Sub-1-V Opeation", discloses a bandgap reference circuit that can operate at supply voltage down to about 1V. This configuration needs two additional resistors, RA and RB, to generate CTAT currents. However, these two resistors will result in more than one opeating point, especially when the drain voltages of PMOS transistors, drops below ΔVbe(i.e., when the two bipolar devices are turns off). Existence of more than one opeating point makes the start-up circuit very complex, or requires an additional circuit to gurantee achievement of a proper operating point. Without such a circuit, the risk of having an undesired operating point is high. : T" Q# Q+ f2 H4 RThis configuration differs from Banba's circuit in several ways. ' q1 w& U0 M7 q Q; Z1. Only one resistor, RC, is added to provide an CTAT current, rather than need two such resistors." \% J4 u' N9 `- s9 l1 k
2. Only one non-zero initial current, and this system will move to this point after power-up. : e2 O4 @9 d, a! I9 k" H: S0 B9 i: O1 z! G& D! D% L# R/ J
Low_voltage_bandgap_reference_circuit.pdf7 N; g; A( x. p, Q) Q4 @
