Auto-range current mirror circuit
AssigneeSilicon Touch Technology Inc.
InventorsFu-Yang Shih, Hsu-Yuan Chin
Life of this patent
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Abstract
An auto-range current mirror circuit has a current sensing circuit, a front and rear stage current mirrors each has an adjustable amplifying rate. The current sensing circuit presets a threshold current and has an input current of the front stage current mirror. The current sensing current compares the input current with a threshold current and then outputs a controlling signal to the front and rear stage current mirrors to adjust a suitable amplifying rate. Therefore, a bias current of the rear stage current mirror is amplified by the suitable amplifying rate to improve the quality of output current of the rear stage current mirror.
Claims16
An auto-range current mirror circuit comprising:
- a front stage current mirror having a first adjustable amplifying rate, a current input adapted to connect to an input current and a current output, and generating a bias current in the current output;
- a rear stage current mirror
- having a second adjustable amplifying rate, an input terminal connected to the current output of the front stage current mirror and at least one output terminal,
- connected to the front stage current mirror in series to have the bias current from the front stage current mirror, and
- amplifying the bias current by the second amplifying rate to generate an output current in the output terminal;
- and
- at least one current sensing circuit, each electronically connects to the front and rear stage current mirrors and the input current and has a preset threshold current, wherein each current sensing circuit outputs a controlling signal to the front and rear stage current mirrors to adjust a suitable amplifying rate according to the present input current.
Dependencies are inferred from the claim text.