Abstract: Methods are disclosed for forming an improved varactor diode having first and second terminals. The methods include providing a substrate having a first surface in which are formed isolation regions separating first and second parts of the diode. A varactor junction is formed in the first part with a first side coupled to the first terminal and a second side coupled to the second terminal via a sub-isolation buried layer (SIBL) region extending under the bottom and partly up the sides of the isolation regions to a further doped region that is ohmically connected to the second terminal. The first part does not extend to the SIBL region. The varactor junction desirably comprises a hyper-abrupt doped region. The combination provides improved tuning ratio, operating frequency and breakdown voltage of the varactor diode while still providing adequate Q.

Abstract: Methods are disclosed for forming an improved varactor diode having first and second terminals. The methods include providing a substrate having a first surface in which are formed isolation regions separating first and second parts of the diode. A varactor junction is formed in the first part with a first side coupled to the first terminal and a second side coupled to the second terminal via a sub-isolation buried layer (SIBL) region extending under the bottom and partly up the sides of the isolation regions to a further doped region that is ohmically connected to the second terminal. The first part does not extend to the SIBL region. The varactor junction desirably comprises a hyper-abrupt doped region. The combination provides improved tuning ratio, operating frequency and breakdown voltage of the varactor diode while still providing adequate Q.

Abstract: An improved varactor diode (20, 50) having first (45) and second (44) terminals is obtained by providing a substrate (22, 52) having a first surface (21, 51) in which are formed isolation regions (28, 58) separating first (23, 53) and second (25, 55) parts of the diode (20, 50). A varactor junction (40, 70) is formed in the first part (23, 53) and having a first side (35, 66) coupled to the first terminal (45) and a second side (34, 54) coupled to the second terminal (44) via a sub-isolation buried layer (SIBL) region (26, 56) extending under the bottom (886) and partly up the sides (885) of the isolation regions (28, 58) to a further doped region (30, 32; 60, 62) ohmically connected to the second terminal (44). The first part (36, 66) does not extend to the SIBL region (26, 56). The varactor junction (40, 70) desirably comprises a hyper-abrupt doped region (34, 54).

Abstract: An improved varactor diode (20, 50) having first (45) and second (44) terminals is obtained by providing a substrate (22, 52) having a first surface (21, 51) in which are formed isolation regions (28, 58) separating first (23, 53) and second (25, 55) parts of the diode (20, 50). A varactor junction (40, 70) is formed in the first part (23, 53) and having a first side (35, 66) coupled to the first terminal (45) and a second side (34, 54) coupled to the second terminal (44) via a sub-isolation buried layer (SIBL) region (26, 56) extending under the bottom (886) and partly up the sides (885) of the isolation regions (28, 58) to a further doped region (30, 32; 60, 62) ohmically connected to the second terminal (44). The first part (36, 66) does not extend to the SIBL region (26, 56). The varactor junction (40, 70) desirably comprises a hyper-abrupt doped region (34, 54).

Abstract: A structure that reduces signal cross-talk through the semiconductor substrate for System-On-Chip (SOC) (2) applications, thereby facilitating the integration of digital circuit blocks (6) and analog circuit blocks (8) onto a single IC. Cross-circuit interaction through a substrate (4) is reduced by strategically positioning the various digital circuit blocks (6) and analog circuit blocks (8) in an isolated wells (10), (12), (16) and (20) over a resistive substrate (4). These well structures (10), (12), (16), and (20) are then surrounded with a patterned low resistivity layer (22) and optional trench region (24). The patterned low resistivity region (22) is formed below wells (10) and (12) and functions as a low resistance AC ground plane. This low resistivity region (22) collects noise signals that propagate between digital circuit blocks (6) and analog circuit blocks (8).

Abstract: A structure that reduces signal cross-talk through the semiconductor substrate for System-On-Chip (SOC) (2) applications, thereby facilitating the integration of digital circuit blocks (6) and analog circuit blocks (8) onto a single IC. Cross-circuit interaction through a substrate (4) is reduced by strategically positioning the various digital circuit blocks (6) and analog circuit blocks (8) in an isolated wells (10), (12), (16) and (20) over a resistive substrate (4). These well structures (10), (12), (16), and (20) are then surrounded with a patterned low resistivity layer (22) and optional trench region (24). The patterned low resistivity region (22) is formed below wells (10) and (12) and functions as a low resistance AC ground plane. This low resistivity region (22) collects noise signals that propagate between digital circuit blocks (6) and analog circuit blocks (8).