Fine grain voltage scaling of back biasing
View Patent ↗An integrated circuit including a substrate, multiple devices, and voltage control devices. The devices may include high threshold, low threshold, and standard threshold voltage devices. The devices and the voltage control devices are distributed across and coupled to the same substrate. Each voltage control device is configured to apply a back bias voltage at one of multiple discrete offset voltage levels. At least one voltage control device applies a first offset voltage level for back biasing high threshold voltage devices and at least one voltage control device applies a second offset voltage level for back biasing low threshold voltage devices. The selection of back biasing is based on relative population density of the different types of devices and varies across the substrate. Fine grain reverse back biasing reduces leakage current while reducing any performance decrease. Fine grain forward back biasing improves performance while reducing any leakage current increase.
1. An integrated circuit, comprising:
a substrate;
a plurality of devices, each of said plurality of devices having a body connection electrically coupled to said substrate, wherein said plurality of devices includes at least one high threshold voltage device and at least one low threshold voltage device; and
a plurality of voltage control devices distributed across said substrate to bias different locations of the same layer of the substrate at different bias voltages, respectively, wherein each of said plurality of voltage control devices has an output electrically coupled to said substrate and is configured to apply a back bias voltage to said substrate at one of a plurality of discrete offset voltage levels relative to a reference supply voltage level;
wherein said plurality of discrete offset voltage levels includes a first offset voltage level for back biasing said at least one high threshold voltage device and a second offset voltage level for back biasing said at least one low threshold voltage device.
2. The integrated circuit of claim 1 , wherein said plurality of discrete offset voltage levels includes a third offset voltage level which is between said first offset voltage and said second offset voltage level, and wherein said plurality of voltage control devices includes at least one voltage control device which is configured to apply a back bias voltage at said third offset voltage level.
3. The integrated circuit of claim 2 , wherein said plurality of devices includes at least one standard threshold voltage device having a medium threshold voltage.
4. The integrated circuit of claim 1 , wherein each of said plurality of voltage control devices comprises a negative charge pump, wherein said plurality of discrete offset voltage levels are reverse back bias voltage levels, wherein said first offset voltage level is less than said second offset voltage level.
5. The integrated circuit of claim 1 , wherein each of said plurality of voltage control devices comprises a voltage regulator, wherein said plurality of discrete offset voltage levels are forward back bias voltage levels, wherein said first offset voltage level is less than said second offset voltage.
6. The integrated circuit of claim 1 , wherein each of said plurality of voltage control devices is dynamically programmable during operation using a corresponding one of a plurality of stored back bias values.
7. The integrated circuit of claim 1 , wherein said substrate is subdivided into a plurality of locales, wherein at least one of said plurality of voltage control devices is located within a corresponding one of said plurality of locales, and wherein said at least one of said plurality of voltage control devices is configured to apply a back bias voltage level based on a relative population of high threshold voltage devices and low threshold voltage devices located within said corresponding one of said plurality of locales.
8. The integrated circuit of claim 7 , wherein said at least one of said plurality of voltage control devices is configured to apply a back bias voltage level based on a relative population of high threshold voltage devices, standard threshold voltage devices, and low threshold voltage devices located within said corresponding one of said plurality of locales.
9. The integrated circuit of claim 1 , wherein said substrate is subdivided into a plurality of regions based on a relative population of high threshold voltage devices and low threshold voltage devices located within each of said plurality of regions, wherein said plurality of regions includes at least one region designated as a high threshold voltage region and at least one region designated as a low threshold voltage region, wherein at least one of said plurality of voltage control devices located within said high threshold voltage region is configured to apply a back bias voltage at said first offset voltage level, and wherein at least one of said plurality of voltage control devices located within said low threshold voltage region is configured to apply a back bias voltage at said second offset voltage level.
10. The integrated circuit of claim 9 , wherein said plurality of discrete offset voltage levels includes a third offset voltage level which is between said first offset voltage and said second offset voltage level, wherein said plurality of regions includes at least one region designated as a medium threshold voltage region, and wherein at least one of said plurality of voltage control devices located within said medium threshold voltage region is configured to apply a back bias voltage at said third offset voltage level.
11. The integrated circuit of claim 1 , wherein said plurality of discrete offset voltage levels includes at least three discrete offset voltage levels separated by a voltage differential in which said first and second voltage levels are separated by at least twice said voltage differential, and wherein adjacent ones of said plurality of voltage control devices are configured to apply back bias voltages which differ by no more than one voltage differential.
12. The integrated circuit of claim 1 , further comprising a configuration block which is configured to apply control values for programming each of said plurality of voltage control devices at a selected one said plurality of discrete offset voltage levels.
13. The integrated circuit of claim 1 , further comprising:
a selection block that is configured to enable each of said plurality of voltage control devices for a selected one of forward back bias and reverse back bias;
wherein each of said plurality of voltage control devices comprises a programmable bias voltage generator; and
a configuration memory which stores a plurality of first control values for programming each of said plurality of voltage control devices to apply a selected one of a plurality of reverse back bias voltage levels, and which stores a plurality of second control values for programming each of said plurality of voltage control devices to apply a selected one of a plurality of forward back bias voltage levels.